T-Mobile Home Internet + Google Nest WiFi

SETTING UP GOOGLE NEST WIFI POINTS WITH T-MOBILE HOME INTERNET

Example 1: You had Google Nest Wifi Points setup with a modem from another provider.

The Google Wifi point plugged into the old modem is the "router" point and all other wifi points are "bridge" points.  Since T-Mobile is a "gateway" that means it's a modem and router all-in-one. 

1. Make sure the wifi point you plug into the T-Mobile gateway is the "router" point (the point that was plugged into your old modem), not one of the "bridge" points. Otherwise you'll have to RESET all wifi points in the mesh just like you had to do when you first setup your Google mesh.  Use the Google Home app if you need to find which point is your Google wifi "router" point.
2. Make sure that your T-mobile gateway network name is DIFFERENT from your Google mesh network name.  The T-mobile gateway is also wireless and if both your gateway and mesh networks have the same network name then you'll have problems (DOUBLE NAT) with devices and apps because your devices and apps will think they're on the same network but in reality some are on the T-Mobile wifi network and some are on the Google wifi mesh network, thus the devices and apps can't "see" each other.  (I.E. Your Roku app can't see your Roku TV or your laptop can't see your wireless printer)
3. Make sure your phone is on the correct network.  In phone settings select your Google Mesh network and connect.  Turn on "prefered network" and "automatically connect network".  All the other networks, the Google Mesh Guest and the T-Mobile network select Forget Network, unselect or turn off "prefered network" and "automatically connect network" so your phone will not automatically connect to the wrong network.  Make sure these settings off in the networks not used as the default setting is on.

Example 2: You have T-Mobile Home Internet and you want to extend it with a Google Mesh Wifi Points or Hubs.

1. The Google Wifi point you plugged into the T-Mobile “gateway” is the “router” point and all other Google wifi points are “bridge” points. 
2. Just pretend that your T-Mobile “gateway” is just a modem, not a router and do the Google Mesh Wifi setup. 
3. Make sure you follow Steps 1-3 in Example 1 as you do the setup.

WARNING: I know in the geek world to have a Google wifi point “router” plugged into the T-Mobile “gateway” router/modem is redundant and we want to FIX IT. 

Some want to make all the wifi points "bridge" points and not have the Google "router" point.  The Google mesh is designed where the Google "router" wifi point controls all the Google "bridge" points.  If you change the router wifi point to a bridge point then your mesh system will NOT work.  

Some want to reconfigure the T-Mobile "gateway" and turn off the router portion of the modem/router combo.  The research I've done suggests this can't be done because the "gateway" modem/router are integrated.