I'm happy to report a solution to the controller unlinking problem if you are using Google Wifi. Using the Google Wifi app, reset the network. This should stop the controller from loosing it's link during gameplay.
I tried connecting directly to the modem bypassing the Google Wifi routers and there was no change other than I get 500 mbps rather than 400 mbps speed on a speed test. Still getting Game Might Stop warnings.
If you are referring to the Gaming Preferred setting in the Google Wifi app then that option is not yet listed in my app. Either I hadn't received the updated app yet or that feature only works with Google Nest Wifi and not Google Wifi. But that point is moot now since today I bypassed the Google Wifi's and it didn't make a difference. I suspect that certain areas are being overloaded with too many users and that is what is causing the slow streaming. I check my Windows 10 network monitor and I am only getting 10 mbps on my game streams even though my speed tests are 50 times faster than that.
@codesplice @Odin1 I also don't see the gaming preferred option from Google WiFi app. I'm using the OG Google router (can't even remember what it's called), and the 1st gen Google WiFi. I did notice the help page was referring to Google Nest Wifi. I wonder if it's only available to the newer models.
Looks like I'm going shopping this black friday...
Try connecting your Ethernet cable directly to the modem and power cycle the modem & restart the computer. I'm guessing it probably won't make a difference, at least it didn't in my case. I can play for about 5 to 10 minutes before I get kicked off due to unstable connection. I really don't think Google Wifi is the issue. It has to be server overload on Google's part. I think they just don't have enough servers to serve everyone. I'm capping out at 10 mb/s on a 400 mb/s connection when playing Stadia in Chrome. When in Youtube and I bring up stats for nerds I get 230000 kb/s speed which equals 230 mb/s. I pass the Project Streaming speed test with an Excellent. I beta tested Project Streaming last year and I had tremendous fun and no issues whatsoever. So the only explanation is server overload.