Connection Constantly Dropping

About a week ago, I started having issues with my home internet.  Devices will briefly connect, but after about 30 seconds they will either say they have connection but no internet or will say they have been paused.  Then they will re-connect, then disconnect, reconnect, etc. endlessly.

This is happening across two different computers and a mobile device, on both Wi-Fi and Ethernet.  None of these devices have issues connecting to other networks.  I've restarted my Gateway and my devices multiple times, messed around with settings, double-checked the cables, etc., but the issue is persisting.

Testing the Internet through the app shows I'm getting good speeds to the Gateway, and will show decides are connected with strong signal even when the devices themselves are showing no connection.

At this point I think it's some software problem with the Gateway, which I cannot fix.  I've scheduled two different service appointments and both have been unceremoniously cancelled (I assume because the diagnostics all show I'm getting good service).  I functionally do not have internet now.  I can't get the assistant to even confirm if the Gateway's firmware has been updated.  Help?