XH2-TC touchscreen lost wi-fi connection after XB8 gateway upgrade

After upgrading from an XB7 to an XB8 gateway, the security touchscreen lost its wi-fi connection and I haven't been able to restore it. I've tried restarting the touchscreen several times, including taking out the battery in the process, and that had no effect. Changing from WPA3 to WPA2 didn't help either (that was something we did for printer connectivity but I'd hoped it might help with this too).

The instructions for pointing the touchscreen to a new gateway (https://www.xfinity.com/support/articles/connect-xh-wireless-gateway) looked promising, but I hit a roadblock after step 4 because the Connectivity menu under Advanced Settings doesn't include an option to "Connect to New Gateway Now." I only have the options for "Test Connectivity" and "Wi-Fi & Cellular Signal Strength," and those just show that the cell signal is fine but there is no wi-fi connection.

Attempted to chat with the AI Assistant but started to lose the will to live LOL so I'm hoping for better luck here. Any suggestions? I did also ask about the issue at our local store and they weren't aware of any fundamental compatibility problem, but we didn't discuss it at any length since I was there for equipment return. Thanks,

Frank