Apple TV sign has an endless loop

For months when I try to use Apple TV on my tcl google tvs, I use the QR code or the log in website, enter my credentials only for the tv to reload to the original screen with a new code. I am told this is an Xfinity issue. I have restarted my tv, my WiFi, cleared caches, data, deleted the app, restarted everything and then reinstalled, to no avail. Please help me, this is maddening!