If I want the WiFi to work. I wasn't even using the WiFi for a long time, because I would have had to enter the username and password manually, you couldn't share WPA Enterprise info with it, you probably still can't.

It started happening sometime after updating the watch. I could try resetting it, but I'm lazy.

It's a watch problem, the phone has no problem. The phone only disconnects when it's not connected to T-Mobile Wi-Fi.