FYI this being part of "April Cools" series heavily implies it's not a real tech issue but a riff on the "We can only send an email within 500 km" / "Can't print on Tuesdays" kind of articles.
> Happy April 1st! This post is part of April Cools Club: an April 1st effort to publish genuine essays on unexpected topics. Please enjoy this true story, and rest assured that the tech content will be back soon!
The post’s disclaimer (and April Cool’s site itself) both imply that the goal is to touch on novel topics and should be genuine content of the author. That said, this story could clearly be apocryphal.
Hi! I helped review this story, and also am one of the organizers of April Cools. Two things:
1. u/obi1kenobi told me it was a real thing that happened to him
2. The point of April Cools is that the things aren't jokes. They're real essays written with care, just outside of the author's usual writing topics. Some of the other ones we got this year are about hydroponics, current events in Sumo wrestling, parenting, and decaf coffee.
Oh, I see. It wasn't a suggestion for a replacement, hence 'org' in there since they were talking about 'organizers'. They could have called themselves the April Tools. Just a dumb joke/unmissable opportunity to call some perfectly nice-seeming internet strangers a bunch of tools.
Like the guy said, you can't be taken seriously. That's the problem with being a April fool. You are just a funny entertaining guy. Not a source of information.
I had more thought of an issue regarding bad grounding (i.e. grounding rods dried out and only work properly when the earth is wet), but trees are even more unexpected.
> Interestingly, objects outside the straight line between antennas can still cause interference! For best signal quality, the Fresnel zone between the antennas should be clear of obstructions. But perfection isn't achievable in practice, so RF equipment like Wi-Fi uses techniques like error-correcting codes so that it can still work without a perfectly clear Fresnel zone.
I wonder if other waves like pressure/audio waves also have a similar effect.
Yes they do. That’s what an echo is, sound waves bouncing off an obstacle between two points. That obstacle doesn’t need to be within the direct line of sight, just within the dispersion area of the outgoing sound wave.
At the far end you’ll hear (although in reality, your brain will almost certainly cover this up for you) distortion caused by the sound wave defracting off the obstacle and interfering with the primary wavefront. Hence the reason why people put so much effort into design concert halls, and adding sound dampening treatments to recording studios. Obstacles will distort sound, but energy absorbing obstacles will distort less.
> At the far end you’ll hear (although in reality, your brain will almost certainly cover this up for you) distortion caused by the sound wave defracting off the obstacle and interfering with the primary wavefront.
I wonder how much polarization affects things; I was once told that terrestrial FM Radio is transmitted with vertical polarization to reduce interference from tall objects between you and the transmitter.
Terrestrial TV (some of which used bands that overlap FM radio) uses horizontal polarization.
My mind was blown when I saw the 4F experiment, where a lens transforms an image into the Fourier domain. I'm not sure if it's related to the Fresnel zone (I think it is not or only very vaguely), but it's pretty amazing:
A widened beam of collimated light (i.e. parallel beams) is sent through e.g. a slide with some image printed on it. Using a lens placed one focal length away, it is focused down to a point (one focal length from the lens). One more focal length from that point, the beam will have reached its original width again, and another lens makes it parallel again, projecting it onto a screen placed one focal length from the second lens:
| () . () |
image lens point lens screen
This will behave exactly as expected at first glance. The image will be visible on the screen (upside down IIRC) and if you hold a piece of paper into the point, you'll just see a single bright dot. However, what's actually present (due to diffraction) is the Fourier transform of the image! If you put an iris around the point, the image on the screen becomes blurry because you just filtered the high frequencies! And what's even more impressive, if you remove the center of the point (e.g. by inserting a glass slide with a small black circle in the middle), you'll get only the high frequencies, and the image on the screen will be the edges of the original image.
I had an experience like this once! My my laptop would inexplicably and intermittently stop connecting to the internet.
It turned out my bluetooth headset was using the same band as the wifi but I only figured this out after a few months and a replaced wifi card. I wouldn't wish that experience on my worst enemy.
Turns out most consumer electronics operate in the same unlicensed consumer bands, so your bluetooth mouse, headset, wifi, and microwave all tussle for the same stuff.
I had a fun one where every time I would get out of my chair my monitors would turn off, turns out the EM fields from the compression/decompression can actually be enormous in some cases.
My Mac Pro desktop used to wake up whenever I used a MacBook Pro in the same room. Obvious thought was, maybe the laptop was sending wake-on-lan packets for some reason. Turns out, the carpeting in that room tends to create static buildup, and my MBP's charger was not grounded. Touching the laptop would send a mild discharge into the wall line, tripping something in the desktop's PSU to wake it up.
I've experienced something similar, but the chair's discharge was interfering with a PCI riser, tripping just over some threshold that would cause the OS kernel to panic and shutdown. It felt so incredibly unbelievable when we first noticed the correlation that we called tons of people over to watch us demonstrate it just to see if there was something else we were missing.
Same, my macbook had unusable wifi when playing music via Bluetooth headphones. Switched to playing from my phone, somehow that worked - probably problem with the BT radio in the laptop since I didn't change wifi channel.
I have a fancy microwave that degrades my fancy bluetooth headset but not others. Did replacing the wifi card work? I'm wondering if I need to switch up my expensive microwave, or expensive headphone, because replacing bluetooth dongle (with another generic one with same chipset) hasn't resolved issue.
Microwaves use the 2.4ghz spectrum but typically not with any real precision which means that while in use they just tank the 2.4ghz spectrum.
*As an aside, one of my favorite things I get to do at work is when onboarding new Jr. Net Engineers is getting them take our spectrum analyzer into our office kitchen and instructing them to watch the spectrum turn bright red while I make a bag of popcorn.
Anyhow to get to your question, the best answer would be to get some distance between your microwave and set-up you're using with the headset. Otherwise if that isn't possible, then you'll want some headphones that does use 2.4ghz. Replacing the microwave will likely not fix the problem since they all use 2.4ghz band for cooking and at least I've never seen one shielded well enough that it didn't impact others while in use.
I remember hearing about a few common failure modes for early internetworking of adjacent buildings. The first being running a bare twisted pair cable between buildings. Worked fine until the next lightning storm, and then a nearby strike fries the equipment on both ends. You have to use grounded conduit to run strands between buildings my dudes.
But the other one was setting up WiFi between buildings, and tended to be more of a problem in academia because the yearly cycles make it a bit more likely. If you set it up in the fall, and everything works all winter until spring comes, when the water in the deciduous tree leaves attenuates the signal. The nasty part of this one is not the failure mode but the timing. Everyone has been happily using and depending on their sweet sweet bandwidth for six months and poof, it’s just gone one fine April morning.
I had one recently - old Nintendo switch; worked fine when docked, couldn't get an internet connection on wifi.
Turns out it had been so long that the wifi MAC was picking up a DHCP address that was blocked at the firewall; the dock had its own MAC so it got a good address.
Were you using an Ethernet adapter? The original switch dock has a DisplayPort to HDMI adapter and USB hub. It doesn’t do anything with networking. The OLED dock adds ethernet (and therefore a second MAC).
The article briefly mentions that this was unbelievable because rain should make Wi-Fi worse not better.
That parallels my experience but I didn’t realize was commonly understood. I noticed that in the hot summer the Wi-Fi reception in my yard (IE, farther from the access point in the house) is worse. Eventually I decided that summer heat is really proxy for humidity and that it wasn’t unreasonable for high water concentration in the air to provide an obstacle to Wi-Fi signal.
The 500 mile email story is one of my favorite reminders that, fundamentally, we're still governed by the laws of physics. It's funny, but it's also a reminder that, while networks might be very fast, the latency is still going to be governed by the speed of light.
Well laws of physics is what gave us radio in the first place.
Some of my favorite video documentaries are on how it was theorized and then slowly developed over years and decades until they finally got to spark-gap transmitters.
But just imagine listening to spark-gap morse code radio broadcasts for years as amateur and then suddenly someone does a broadcast test of actual voice (violin!) That must have been incredible to hear wirelessly.
24 December 1906 Reginald Fessenden, that was the leap that eventually gave us wifi
I actually like thinking about the exchange of physical information as a network propagation delay, and entanglement/coherence as a distributed consensus algorithm. They're kinda samey from a conceptual point of view (in my amateur opinion)
DNS responses sent over UDP are often truncated if the response is too large. This manifests itself as "machine unreachable if name > x characters" sort of errors when you have really long FQDNs.
I remember one (might have been a hn-er's comment, dunno) about the computer restarting when the toilet was flushed. Turns out it was due to voltage drop when a compressor turned on to refill the reservoir of the toilet.
That's why in rural locales with spotty power it pays to have a UPS on any electronics -- you might not benefit much from 15-30 minutes of extra power in a day long blackout, but it keeps everything happy when the voltage fluctuates.
My personal example: VoIP phones stopping after the Asterisk server was up for 3 days.
Reason: the server had IPv6 turned on, and it steadily accumulated privacy IPv6 addresses. These addresses were all sent in a packet describing the supported media endpoints, using UDP.
And yep, eventually it overflowed the MTU and the phones couldn't handle the fragment reassembly.
Thanks. I've never run Asterisk on Ubuntu. FreePBX is CentOS based which is mostly what I've run Asterisk on. I only started to worry about Ubuntu around 2012.
That mad IPv6 address thing must have stuffed up more than just a VoIP negotiation packet. DNS switches from UDP to TCP when responses get too large.
DNS is affected, but differently. It's mostly DNSSEC signatures that cause trouble nowadays.
SIP is special because the signalling and media protocols are separate. So when a call is being established, the parties exchange their media endpoint locations. This necessarily means that the server has to list its IPs (or DNS names) so that the client can choose the best one. And as a quirk of SIP, it sends the entire set for each of its supported codecs.
Yes, I know, just like ftp 8) I do hope that whomever invented putting the control channel in a separate stream from the data is mildly discomforted. Mind you, all that stuff was invented a very long time ago, when trousers were a major trip hazard.
My go to fix is "symmetric RTP", which seems to have become a default over the last decade or two.
I did tech support via phone for a popular consumer computer brand. One particular call, a woman reported that her computer was restarting every time someone in the house flushed the toilet.
Long story short, her home was in the back-back woods with the home powered by a generator. In addition to powering the computer, the generator was also the source of power for a water pump which would kick on to refill the toilet bowl whenever it emptied. And wouldn't you know that that water pump had a beefy coil around its motor and would brownout the entire house every time it started?
I have a similar one, with an automated monorail hoist. The engineer who started the job had ordered the monorail hoist with a control cabinet with Ethernet comms to tell it where to move (instead of just controlling the hoist directly from the main control cabinet.) After days' worth of shenanigans trying to troubleshoot seemingly random comms drop-outs I'd narrowed it down to only occurring when the hoist was being lowered under load, which led me to the Ethernet cable in the hoist cabinet which ran parallel to the motor cables from the hoist's 6kW VSD. Whenever it lowered, the EMI was enough to nuke the Ethernet connection. Re-routed the Ethernet cable and after that it ran fine.
A user was having a really bizarre problem: They could log in when they were sitting down in a seat in front of the keyboard, but when they were standing in front of the keyboard, their password didn't work! The problem happened every time, so they called for support, who finally figured it out after watching them demonstrate the problem many times:
It turned out that some joker had rearranged the numbers keys on the keyboard, so they were ordered "0123456789" instead of "1234567890". And the user's password had a digit in it. When the user was sitting down comfortably in front of the keyboard, they looked at the screen while they touch-typed their password, and were able to log in. But when they were standing in front of the computer, they looked at the keyboard and pressed the numbers they saw, which were wrong!
Thanks for mentioning! I would love more submissions! I have a few stories in my backlog to read and vet, but not enough. I'll be going through this thread and adding more that haven't been added yet.
I had a customer who used a line of sight system for extending their network across part of a city.
I had a shortcut on my desktop with the weather for that town ready when they would inevitably call and blame our unrelated equipment for some problem.
I worked at a small, local ISP in the 90:ies that had a point to point link across the river, handling the dial up traffic from the telecom company we partnered with.
Every few days, always at roughly the same time, all incoming dial up traffic would drop. A minute later, the customers could reconnect.
It took a while before we realized that one of the huge passenger ferries that docked a short distance upstream was the cause. When it arrived and departed, its chimneys and possibly bridge and highest deck blocked LOS across the river.
I used to work in high-frequency trading. I had several tabs permanently open to the live weather radar feed for regions where we had microwave towers: the NE USA, the South of England, the Alps...
I'm curious to know where your towers were. Do you know if they still exist? Were your microwave antennae co-located on other operators' towers (e.g. those for VHF radio), or did your company have towers all to itself?
Without going into anything confidential - we had some of our own hardware, but generally rented capacity from firms like [0]. Some towers were custom built for HFT, some were shared with other types of users.
A famous blog post investigating some of the towers as an outsider, at [1], will be of interest to you.
If you want to guess where they are, get a globe, find the datacentres where electronic exchanges operate (it's not a secret: Chicago, New Jersey, London, Tokyo, Frankfurt, Zurich...) and draw the straightest possible lines between pairs of them. Microwaves don't cross the ocean.
Traditional optical fiber has glass in the middle. The speed of light in glass is only about 66% of the speed in air, so microwave is always faster if you can get a reasonably straight path for both.
There now exists hollow-core fiber, where the light travels down an air gap in the middle, which is theoretically competitive with microwaves/lasers/etc. How much this is being used is a secret, but microwave transmission definitely hasn't gone away.
I used to be in an adjacent field and we used to joke about when the HFT guys were gonna get working on some neutrino detectors & sources to signal straight through the Earth. You could use them for science on the weekends!
Sounds awesome, to be able to send a signal directly through the whole earth from point to point. It also sounds like origin story of X-Men or a new cancer
My recent version: I was playing a pinball game in an arcade. One particular ramp shot was registering earlier in the day and then stopped working.
Eventually I realized that the sensor is an optical beam, and the receiver happened to be in direct sunlight coming in through a window! So it was continuously receiving infrared and would never report the beam being blocked by a pinball. Sure enough, it started working again once the sun angle changed by a few more degrees.
Heh, but not exactly. If I blocked the sun, the receiver still would have been picking up the real beam. I would have had to block the sun _and_ make the shot with a pinball at the same instant... which is just playing the game normally with extra steps.
I have an optical smoke detector that will give (very loud) false alarms if a sun beam can bounce off a windowsill onto it. It works great if the curtain is closed. Debugging that took a few early sunrises.
Oh man, this is one of my favorite lines of all time:
> "Anyway, I asked one of the geostatisticians to look into it--"
> "Geostatisticians..."
> "--yes, and she's produced a map showing the radius within which we can send email to be slightly more than 500 miles. There are a number of destinations within that radius that we can't reach, either, or reach sporadically, but we can never email farther than this radius."
I adore when experts use their expertise to analyze real-world things like this and provide ridiculously thorough explanations :-D
My favorite story kinda of this nature, of an expert as alien intelligence, was Feynmann's calculations about computer architecture of the Connection Machine:
It's a few paragraphs, maybe too much to quote, but the bulk of it starts with:
> By the end of that summer of 1983, Richard had completed his analysis of the behavior of the router, and much to our surprise and amusement, he presented his answer in the form of a set of partial differential equations. To a physicist this may seem natural, but to a computer designer, treating a set of boolean circuits as a continuous, differentiable system is a bit strange. [...] Our discrete analysis said we needed seven buffers per chip; Feynman's equations suggested that we only needed five. We decided to play it safe and ignore Feynman.
Guess who was right.
The whole essay is worth reading, if you haven't yet.
As someone with very limited electrical experience, the more magic switch story instantly went "the second terminal of the switch is probably grounded to the switch casing" when they explained it only had one connected terminal.
This is a very common thing in older automotive electronics, for example.
There was a site with stories like these somewhere, I sadly can't remember the URL any more.
I think the one that stuck out to me was the Soviet mainframe computer that would get weird bit flips almost every day, always at the exact same time. Somebody compared what was different about the days it didn't get bit flips on, it turns out those were the days on which a particular train didn't run, the computer was very close to a railway station. What train was it, you ask? The one transporting the (definitely perfectly safe to eat, definitely not filled to the brim with nuclear radiation) cow meat from Chernobyl. The radiation was intense enough to cause bit flips, I'm sure the quality of soviet components didn't help here either.
The title might've been a Fleetwood (the other kind of) Mac reference.
o/~ Wi-Fi's only working when it's rainin'
Players only stutter when they're buff'rin'
Websites, they will page load oh so slooooww
When the rain falls down, you can download
Actually experience the same thing but for different reasons.
I've lived in the same place for 25 years, so I've seen the invention of wifi and then checking every few months for other users on wifi analyzer, I've seen it grown and grown.
Well in that 25 years they've built so many surrounding apartment complexes that the 2.4ghz saturation is absolutely insane. I cannot believe how many networks show up on the analyzer in 2024, has to be well over 100.
But when it rains, it cuts off dozens of those other apartments, and I get better signal inside my own apartment.
20ish years ago I hung out in an IRC channel in which, during autumn/winter months, one person would frequently get disconnected and when he came back complained about foggy weather.
He had a laser line or sight connection. It could handle rain (with some degradation), but thick fog killed it.
Yeah. If you're outside during a calm day with snow falling, it's unusually quiet because large fluffy snowflakes absorb sound. Fog does something very similar to optical or radio systems. Rain has much bigger droplets and far fewer of them. :)
Funny. A few years ago I was on #chicken, and there was a person frequently connecting and disconnecting. Turns out they were on a boat and the motion of the boat would be enough to disrupt their wifi directional antenna.
They were rigging a servomechanism to automatically aim the antenna and wanted to write the control software in Chicken Scheme (for whatever reason, never questioned because Chicken is fun).
(I'm the author.) I really like trees! So I wouldn't have wanted to cut it down or even prune it.
Also, I hate operational (ongoing) solutions to problems. Pruning it would have been exactly that kind of solution -- we'd have had to prune it regularly or else it would have kept being a problem every so often.
The hardware fix was easier: our equipment was already a bit old and slow, the upgrade fixed the rain problem while also making it faster, and it's not something we've had to tweak since. I've long since moved out, but my parents still use that same 802.11n bridge today!
I once had a Time Warner tech blame the moisture content of the air for impacting the copper cabling to explain outages at our apartment. This both makes more sense and, I suppose, is more interesting.
My parents’ house was connected to old copper phone lines from ca. 1940, and by the 1980s rain intrusion from long or heavy storms would cause massive static on the line (made worse when squirrels ran on the line). This was disastrous when I got my first modem ca 1986. Just unusable until it dried out.
Interesting! This was a relatively new apartment building in Hollywood with similarly aged cable — maybe he was right and I'm altogether wrong. They ran the cable up through vertically adjacent units as well which left you at some degree of mercy of your downstairs neighbors.
At Pinterest, when we were working from one of the founder's apartment, the internet went down. Lots of debugging later and we traced it to a cable that a squirrel had chewed threw..
Could also have be that the neighbor have a not compliant WiFi device that send out deauthentication packages, then it would also work better during rain.
This reminds me of when I took my PS5 to my family's house for Christmas vacation. We both have the same SSID because I set up both access points but they changed the password when they forgot it because they're a bunch of bozos.
My PS5 controller refused to connect to my PS5 and I couldn't figure out why. I gave up and after a few days tried again only to realize that the PS5 controller can't connect to the PS5 wirelessly when the wifi was connected but the password was invalid. I still don't know why it was a problem or if it still is a problem but it was a monster to debug. lol
The reason I didn't fix the wifi in the first place was that I didn't have a spare USB C to USB A cable to hardwire my controller and I was playing a singleplayer game. I think it was last of us.
I dislike calling this "magical thinking", just because the plausible causal relationship takes a little time to discover, it's not implausible at the outset.
In fact, the causal relationship between rain & wifi is taken as a given by the author:
> If anything, rain makes wireless signal quality worse
It's not too surprising to discover a causal relationship between two things we already know are causally related.
My guess was that the directional antennas were off by enough that it didn't work well in clear conditions, but the rain refracted the signal enough to work. The actual answer was better :D
I know of a case in the Caribbean where where a line of sight connection between two buildings of a bank was being interrupted by a tree from a competitor bank. They asked the competitor would they mind cutting the tree and the answer was sure for the small fee of 1 million, Third hand info but I did hear from a network guy I worked with.
The real lost opportunity here was figuring out the cost of running fiber instead of wireless and charging the $1 less than that for the tree trimming.
I recall there was a story about a computer mouse not working when it was sunny? It had to do with the sensor. I can't find it so I'm starting to doubt if that actually happened...
I had experienced this one and felt like I was going mad, and then I guess the humidity changed and I gave up/stopped thinking about it. It wasn't until a couple years later I saw a post here about the gas cylinders causing monitors to blank.
There's a Mister Bean episode in which his TV will only work when he's sitting next to it (where he obviously cannot see it). I think he manages to watch TV by creating a copy of himself with his clothes next to the TV, while he's sitting naked in front of it
I recall reading a variant of that where a terminal had a "print screen" button, and the claim was it would work when standing but not when sitting down (or was it vice versa).
In the end there were two print screen buttons, only one of them functional, and one of them more obvious when standing (or sitting).
These kind of stories are classic debugging parables that teach you to step back and consider what you may be assuming incorrectly when something absolutely doesn't make sense or seems impossible.
330 comments
[ 104 ms ] story [ 312 ms ] threadThe post’s disclaimer (and April Cool’s site itself) both imply that the goal is to touch on novel topics and should be genuine content of the author. That said, this story could clearly be apocryphal.
1. u/obi1kenobi told me it was a real thing that happened to him
2. The point of April Cools is that the things aren't jokes. They're real essays written with care, just outside of the author's usual writing topics. Some of the other ones we got this year are about hydroponics, current events in Sumo wrestling, parenting, and decaf coffee.
The org name April Tools was right there!
> Interestingly, objects outside the straight line between antennas can still cause interference! For best signal quality, the Fresnel zone between the antennas should be clear of obstructions. But perfection isn't achievable in practice, so RF equipment like Wi-Fi uses techniques like error-correcting codes so that it can still work without a perfectly clear Fresnel zone.
I wonder if other waves like pressure/audio waves also have a similar effect.
[1] - https://en.wikipedia.org/wiki/Fresnel_zone
(Side note, is this story old? 802.11n isn't particularly new enough to upgrade to.)
At the far end you’ll hear (although in reality, your brain will almost certainly cover this up for you) distortion caused by the sound wave defracting off the obstacle and interfering with the primary wavefront. Hence the reason why people put so much effort into design concert halls, and adding sound dampening treatments to recording studios. Obstacles will distort sound, but energy absorbing obstacles will distort less.
See: https://en.wikipedia.org/wiki/Human_echolocation
FTA:
> At the time, I was still a college student — this was over 10 years ago.
Terrestrial TV (some of which used bands that overlap FM radio) uses horizontal polarization.
A widened beam of collimated light (i.e. parallel beams) is sent through e.g. a slide with some image printed on it. Using a lens placed one focal length away, it is focused down to a point (one focal length from the lens). One more focal length from that point, the beam will have reached its original width again, and another lens makes it parallel again, projecting it onto a screen placed one focal length from the second lens:
This will behave exactly as expected at first glance. The image will be visible on the screen (upside down IIRC) and if you hold a piece of paper into the point, you'll just see a single bright dot. However, what's actually present (due to diffraction) is the Fourier transform of the image! If you put an iris around the point, the image on the screen becomes blurry because you just filtered the high frequencies! And what's even more impressive, if you remove the center of the point (e.g. by inserting a glass slide with a small black circle in the middle), you'll get only the high frequencies, and the image on the screen will be the edges of the original image.(I'm the author of the post btw)
It turned out my bluetooth headset was using the same band as the wifi but I only figured this out after a few months and a replaced wifi card. I wouldn't wish that experience on my worst enemy.
I had a fun one where every time I would get out of my chair my monitors would turn off, turns out the EM fields from the compression/decompression can actually be enormous in some cases.
Wait, can you elaborate? I have the same and I thought I was hallucinating or tripping a cable somewhere.
https://www.theregister.com/2020/01/09/office_chair_emission...
Update: reading the reg one, it also had no cusions, it was a standard herman miller so it was a mesh bottom and back.
It would interfere with the Bluetooth signal.
The worst interference problem I've heard of is how USB 3.0 uses 2.4ghz and therefore can cause problems with devices connected with it.
*As an aside, one of my favorite things I get to do at work is when onboarding new Jr. Net Engineers is getting them take our spectrum analyzer into our office kitchen and instructing them to watch the spectrum turn bright red while I make a bag of popcorn.
Anyhow to get to your question, the best answer would be to get some distance between your microwave and set-up you're using with the headset. Otherwise if that isn't possible, then you'll want some headphones that does use 2.4ghz. Replacing the microwave will likely not fix the problem since they all use 2.4ghz band for cooking and at least I've never seen one shielded well enough that it didn't impact others while in use.
https://www.theguardian.com/science/2015/may/05/microwave-ov...
But the other one was setting up WiFi between buildings, and tended to be more of a problem in academia because the yearly cycles make it a bit more likely. If you set it up in the fall, and everything works all winter until spring comes, when the water in the deciduous tree leaves attenuates the signal. The nasty part of this one is not the failure mode but the timing. Everyone has been happily using and depending on their sweet sweet bandwidth for six months and poof, it’s just gone one fine April morning.
Turns out it had been so long that the wifi MAC was picking up a DHCP address that was blocked at the firewall; the dock had its own MAC so it got a good address.
Had to sit down and think about it for awhile before I realized it had to be the firewall blocking access somehow.
That parallels my experience but I didn’t realize was commonly understood. I noticed that in the hot summer the Wi-Fi reception in my yard (IE, farther from the access point in the house) is worse. Eventually I decided that summer heat is really proxy for humidity and that it wasn’t unreasonable for high water concentration in the air to provide an obstacle to Wi-Fi signal.
http://www.ibiblio.org/harris/500milemail.html
Or the Magic/More Magic switch
http://www.catb.org/jargon/html/magic-story.html
It's fun when physical reality meets the abstract models that we have built in our heads of these machines.
Some of my favorite video documentaries are on how it was theorized and then slowly developed over years and decades until they finally got to spark-gap transmitters.
https://en.wikipedia.org/wiki/Timeline_of_radio
But just imagine listening to spark-gap morse code radio broadcasts for years as amateur and then suddenly someone does a broadcast test of actual voice (violin!) That must have been incredible to hear wirelessly.
24 December 1906 Reginald Fessenden, that was the leap that eventually gave us wifi
https://en.wikipedia.org/wiki/Reginald_Fessenden
https://www.youtube.com/watch?v=9eyFDBPk4Yw
https://americanhistory.si.edu/collections/nmah_692464
> If the problem had had to do with the geography of the human recipient and not his mail server, I think I would have broken down in tears.
https://bugs.launchpad.net/ubuntu/+source/cupsys/+bug/255161...
https://news.ycombinator.com/item?id=39898272
Reason: the server had IPv6 turned on, and it steadily accumulated privacy IPv6 addresses. These addresses were all sent in a packet describing the supported media endpoints, using UDP.
And yep, eventually it overflowed the MTU and the phones couldn't handle the fragment reassembly.
That mad IPv6 address thing must have stuffed up more than just a VoIP negotiation packet. DNS switches from UDP to TCP when responses get too large.
SIP is special because the signalling and media protocols are separate. So when a call is being established, the parties exchange their media endpoint locations. This necessarily means that the server has to list its IPs (or DNS names) so that the client can choose the best one. And as a quirk of SIP, it sends the entire set for each of its supported codecs.
Yes, I know, just like ftp 8) I do hope that whomever invented putting the control channel in a separate stream from the data is mildly discomforted. Mind you, all that stuff was invented a very long time ago, when trousers were a major trip hazard.
My go to fix is "symmetric RTP", which seems to have become a default over the last decade or two.
I did tech support via phone for a popular consumer computer brand. One particular call, a woman reported that her computer was restarting every time someone in the house flushed the toilet.
Long story short, her home was in the back-back woods with the home powered by a generator. In addition to powering the computer, the generator was also the source of power for a water pump which would kick on to refill the toilet bowl whenever it emptied. And wouldn't you know that that water pump had a beefy coil around its motor and would brownout the entire house every time it started?
https://github.com/danluu/debugging-stories
It turned out that some joker had rearranged the numbers keys on the keyboard, so they were ordered "0123456789" instead of "1234567890". And the user's password had a digit in it. When the user was sitting down comfortably in front of the keyboard, they looked at the screen while they touch-typed their password, and were able to log in. But when they were standing in front of the computer, they looked at the keyboard and pressed the numbers they saw, which were wrong!
https://thedailywtf.com
https://www.snopes.com/fact-check/cone-of-silence/
[1] https://news.ycombinator.com/item?id=37584399
I had a shortcut on my desktop with the weather for that town ready when they would inevitably call and blame our unrelated equipment for some problem.
Every few days, always at roughly the same time, all incoming dial up traffic would drop. A minute later, the customers could reconnect.
It took a while before we realized that one of the huge passenger ferries that docked a short distance upstream was the cause. When it arrived and departed, its chimneys and possibly bridge and highest deck blocked LOS across the river.
A famous blog post investigating some of the towers as an outsider, at [1], will be of interest to you.
If you want to guess where they are, get a globe, find the datacentres where electronic exchanges operate (it's not a secret: Chicago, New Jersey, London, Tokyo, Frankfurt, Zurich...) and draw the straightest possible lines between pairs of them. Microwaves don't cross the ocean.
[0] https://www.mckay-brothers.com/
[1] https://sniperinmahwah.wordpress.com/2014/09/25/hft-in-my-ba...
There now exists hollow-core fiber, where the light travels down an air gap in the middle, which is theoretically competitive with microwaves/lasers/etc. How much this is being used is a secret, but microwave transmission definitely hasn't gone away.
[0] magic-story
Eventually I realized that the sensor is an optical beam, and the receiver happened to be in direct sunlight coming in through a window! So it was continuously receiving infrared and would never report the beam being blocked by a pinball. Sure enough, it started working again once the sun angle changed by a few more degrees.
> "Anyway, I asked one of the geostatisticians to look into it--"
> "Geostatisticians..."
> "--yes, and she's produced a map showing the radius within which we can send email to be slightly more than 500 miles. There are a number of destinations within that radius that we can't reach, either, or reach sporadically, but we can never email farther than this radius."
I adore when experts use their expertise to analyze real-world things like this and provide ridiculously thorough explanations :-D
https://longnow.org/essays/richard-feynman-connection-machin...
It's a few paragraphs, maybe too much to quote, but the bulk of it starts with:
> By the end of that summer of 1983, Richard had completed his analysis of the behavior of the router, and much to our surprise and amusement, he presented his answer in the form of a set of partial differential equations. To a physicist this may seem natural, but to a computer designer, treating a set of boolean circuits as a continuous, differentiable system is a bit strange. [...] Our discrete analysis said we needed seven buffers per chip; Feynman's equations suggested that we only needed five. We decided to play it safe and ignore Feynman.
Guess who was right.
The whole essay is worth reading, if you haven't yet.
https://en.m.wikipedia.org/wiki/Thinking_Machines_Corporatio...
One thought I had while reading this was what areas of technologies are still open to amateurs.
This is a very common thing in older automotive electronics, for example.
I think the one that stuck out to me was the Soviet mainframe computer that would get weird bit flips almost every day, always at the exact same time. Somebody compared what was different about the days it didn't get bit flips on, it turns out those were the days on which a particular train didn't run, the computer was very close to a railway station. What train was it, you ask? The one transporting the (definitely perfectly safe to eat, definitely not filled to the brim with nuclear radiation) cow meat from Chernobyl. The radiation was intense enough to cause bit flips, I'm sure the quality of soviet components didn't help here either.
https://beza1e1.tuxen.de/lore/index.html
Also posted on HN awhile back:
https://news.ycombinator.com/item?id=23005140
Edit: yep, here are your Crash Cows: https://beza1e1.tuxen.de/lore/crash_cows.html
Discussed many times here in HN:
1. https://news.ycombinator.com/item?id=37576633
2. https://news.ycombinator.com/item?id=23775404
3. https://news.ycombinator.com/item?id=9338708
I've lived in the same place for 25 years, so I've seen the invention of wifi and then checking every few months for other users on wifi analyzer, I've seen it grown and grown.
Well in that 25 years they've built so many surrounding apartment complexes that the 2.4ghz saturation is absolutely insane. I cannot believe how many networks show up on the analyzer in 2024, has to be well over 100.
But when it rains, it cuts off dozens of those other apartments, and I get better signal inside my own apartment.
20ish years ago I hung out in an IRC channel in which, during autumn/winter months, one person would frequently get disconnected and when he came back complained about foggy weather.
He had a laser line or sight connection. It could handle rain (with some degradation), but thick fog killed it.
They were rigging a servomechanism to automatically aim the antenna and wanted to write the control software in Chicken Scheme (for whatever reason, never questioned because Chicken is fun).
This made me smile. My brain autocompleted the fix to something like "help the neighbors trim their tree", but of course the fix is new hardware.
Also, I hate operational (ongoing) solutions to problems. Pruning it would have been exactly that kind of solution -- we'd have had to prune it regularly or else it would have kept being a problem every so often.
The hardware fix was easier: our equipment was already a bit old and slow, the upgrade fixed the rain problem while also making it faster, and it's not something we've had to tweak since. I've long since moved out, but my parents still use that same 802.11n bridge today!
And the same upgrade would often fix it
My PS5 controller refused to connect to my PS5 and I couldn't figure out why. I gave up and after a few days tried again only to realize that the PS5 controller can't connect to the PS5 wirelessly when the wifi was connected but the password was invalid. I still don't know why it was a problem or if it still is a problem but it was a monster to debug. lol
The reason I didn't fix the wifi in the first place was that I didn't have a spare USB C to USB A cable to hardwire my controller and I was playing a singleplayer game. I think it was last of us.
In fact, the causal relationship between rain & wifi is taken as a given by the author:
> If anything, rain makes wireless signal quality worse
It's not too surprising to discover a causal relationship between two things we already know are causally related.
Edit: Found it: https://news.ycombinator.com/item?id=37585548
Not sure how you're styling your links, but in a dark mode view, they are effectively illegible.
https://imgur.com/a/aSbpVF8
Can log in while sitting down, can't log in when standing up.
I need to find the reference ...
Edit: OK, here's one version:
https://www.reddit.com/r/talesfromtechsupport/comments/3v52p...
https://news.ycombinator.com/item?id=21978004
[Edit: I see this one has also been mentioned a few times already in the thread]
In the end there were two print screen buttons, only one of them functional, and one of them more obvious when standing (or sitting).
These kind of stories are classic debugging parables that teach you to step back and consider what you may be assuming incorrectly when something absolutely doesn't make sense or seems impossible.