TMO G4AR and MYQ Help

@tennisfan10 this is a common problem for IoT devices like thermostats, printers, and cameras. Here is my standard reply: (you need to add a separate SSID with a WPA security standard to allow the device to connect to the gateway).

You just need to add a second, 2.4 GHz network with reduced security. 

Some devices cannot connect to the gateway’s default network.  You want to leave this network alone and ADD a second network with the + sign at the bottom of the Network tab in the T-Mobile Internet app.  For this new network, set the band to 2.4 GHz and set the WPA version to WPA/WPA2.  Try connecting your device to this second network.  Use the default network for your other devices as much as possible.

Here are the T-Mobile support instructions for how to add the second network with the app.

Android  How to create additional Wi-Fi networks | T-Mobile Internet app | Android | T-Mobile Support

iOS  How to create additional Wi-Fi networks | T-Mobile Internet app | iOS | T-Mobile Support