@RejZoR WiFi
is hard to understand. Not only do neighboring WiFi AP's interact and interfere with our networks, but also, 'invisible' interference too (non-WiFi interference) that can make it impossible for a normal person to understand why the network is no longer stable.
But the way to a stable network is straightforward. And 'understanding' what went wrong isn't a requirement either.
The routers we're using here are not at the level of appliances yet, nor are they a 'known' quantity either that can be easily tracked and fixed on a running network. They can and do 'suddenly' cause issues on their own too.
After trying all the suggestions people offer here, and seeing no improvement, I would suggest a
full and complete reset of the router and network devices.
Fully Reset Router and Network
There is no 'full reset of Windows 10' from a cloud copy. That has never worked for any serious issues I've seen. A full and complete 'clean' install is the only thing I've seen work.
An overview of the steps I would take would include following the suggestions in the link above, use new SSID's and do not use any saved backup config files or other old customizations or scripts after fully resetting the router. If you feel you must include customizations that 'once worked', add them one at a time to your network, slowly. Testing fully before introducing another variable.
Edit: at the very least, after doing the above and finding no success with your network, you would at least know that it was the
router (hardware?) that was at fault then. And to be clear, I would reset the router fully before I attempted to reset the Windows 10 computers (if at all).
