Ask HN: Help with backups

My current situation is this: I have a desktop computer on Windows 10, a Surface Pro 4 on Windows 10, and a Macbook Air on some version of OS X. (it's my wife's main computer, and she hates updates because they usually change something about the interface. she's probably on at least Yosemite) We each have an external USB drive for storing data. Mine is a 500GB spinning platter, I don't know about hers but it's also spinning platter. My desktop has two hard drives: 128GB SDD and 1TB spinning platter. We also have a Drobo 5N NAS on the network, attached to a many year old Airport Extreme. My wife's computer has Carbon Copy Cloner set to run a clone to the NAS every day or every other day or something, but it fails all the time because it takes so long to interact with the NAS, so actual updates to the backup usually take at least a week, sometimes a month, to actually finish.

This is all a bit of an ad-hoc setup that sort of evolved as time went on with no real planning, and I'd like to put together something nice that isn't quite so rickety. I'm also open to updating the router to something else to promote faster backups across the network to something in the house. (I've been thinking about building a computer that acts as a router for a while based on an Ars Technica article, so now might be the time!) I'm also open to changing out the current NAS for something else if it'll help backups run faster, or for whatever other good technical reason. Don't be shy to suggest hardware. If I need to make something fit in my budget, I can cut out bits until later, or find something cheaper, etc.

(see my first comment for the last bit of this)