Nest Doorbell (battery) won't connect to WiFi

I've had the Nest Doorbell (battery) for a few months with no issues. This week, the doorbell lost its connection and I thought it was a battery issue since it was reported at 10%, although I thought it was weird that I did not receive a notification. I then tried to reconnect the doorbell and it didn't work. I tried resetting to factory settings, rebooting the phone - nothing worked. I was on the phone with Google support for more than an hour and they eventually sent a replacement doorbell. When I tried to connect that one, it connected on the first try, but then the setup did not complete. I tried multiple times after that and it still did not connect. I got back on a call with Google support and the doorbell connected, but only through my mobile hotspot so they say it's something with the Xfinity WiFi router. I have no idea what the problem could be.