The Xfinity TV set-top boxes were not designed to run in this configuration. When the STBs lose Wi-Fi connectivity, for whatever reason, they contact the Xfinity Gateway over a special hidden Wi-Fi SSID to obtain new Wi-Fi credentials, and use those to reconnect to Wi-Fi. That is why it reconnects to the Xfinity Gateway, even though the Wi-Fi connection is poor.
If you run in Bridge Mode, with your own router, have a different username/passphrase configured in your Wi-Fi router than what you have in the Gateway, then the set-top box will not reconnect to Wi-Fi.
The most stable way to use an external Wi-Fi mesh with an Xfinity Gateway is to disable Wi-Fi on the gateway and configure the same Wi-Fi network name and passphrase on your Wi-Fi mesh as what you had configured on the Gateway.
@bstotes wrote:
Would I get the same result of I just disable the WiFi on the gateway and didn't change my mesh network name?
Okay, but keep in mind that that whenever your set-top boxes reboot or disconnect from the network, they will contact the Gateway to obtain Wi-Fi credentials, and will then try to connect to Wi-Fi with those credentials.
So.... change the Wi-Fi network name/passphrase on the Gateway to match your Wi-Fi mesh, then disable Wi-Fi on the Gateway. (In this configuration, your Wi-Fi mesh should be in Bridge/AP mode). Reboot your set-top boxes and they should now auto-connect to your Wi-Fi mesh.
