I have access to both the cable modem and the wifi router, but nothing I've seen there looks unusual. I've reset both to factory settings, and the ISP has just completed their own "reset" of the modem. I'm sitting here with my Windows 10 PC still having
its connectivity issues, with my iPad Pro right next to it, connected to exactly the same access point, just showing my paid for plan 50MBs download, and no interruptions in connectivity.
Baffling!!
The other device I mentioned may in fact be working normally now, but it is too time consuming to run back and forth to the shop to check its status. I'm back thinking I have a PC Windows 10 problem....
Here's another bit of info: the symptoms on the PC are web page won't load (can't find it or won't connect to server). Sometimes, just the act of trying to open a web page severs the Wifi; in that case, connecting to a different access point will bring back
the internet, but the page might not load --- but then does after a refresh, or even stranger, after opening the access point properties box, and then closing it. Very large traffic sites seem to be more accessible than others, like Amazon. One that I have
been unable to open no matter what shenanigans I try: my ISP's customer log in page. To communicate with them, I use the iPad.