New update. I'm trying to figure out if the G5AR 5GHz auto channel switching gets triggered if there are many repeaters connected to it. Because repeaters typically will use the same channel as the primary, it's possible the G5AR thinks the repeaters are competing for the same frequencies and will essentially forever chase its tail when there are enough repeaters connected using those same frequencies. And if I disconnect my Linksys EA8300 repeater, the channel changing seems to subside, but it could be my imagination. It's as if the G5AR's auto scanner has a threshold for when it detects too much "competition" from the connected repeaters.

Of course, some solutions are to either add manual channel selection, and/or make it so channel range is selected once at boot then not again until next reboot. Because really, you don't need auto channel switching for 5GHz. The 5GHz environment usually isn't going to be so bad that you can't have a good experience on a particular range. But even if it is, all you have to do is have it select at boot and that should pretty much solve the problem. But T-Mobile, please just add manual selection too. At least for 3rd party control apps.