google chromecasts and other streaming issues

This may help out with Chromecast and Google Home issues. By default, the TMobile Gateway sets up 3 wifi radios for wifi, all with the same SSID name, one on 2.4GHz (SSID1), one on 5Ghz low (SSID5) and one on 5GHz high (SSID9). It seems that the Chromecast doesn't see SSID5 and SSID9 as the same network, even if they have the same name. So, if your Google Home device happened to connect to SSID5 and your Chromecast connected to SSID9, they appear to be on different networks and will not see each other. 

My solution was to go into the web based router login page for the gateway and turn off one of the 5GHZ radios, so there is only one enabled and it will force both devices to connect to the same one. In my case, I disabled SSID5 and they both reconnected to SSID9 and were able to find each other.

I hope this helps.