For anyone else interested in doing this. Just received the T-Mobile gateway, and set it up using the T-Mobile app (as directed in the instructions). When you do that, it disables the ability of the HINT Control app to login as admin.
The solution for me was simple. I factory reset the gateway, and directly connected it to my iMac using ethernet. I then used HINT Control on the iMac to shut down the 2.4GHz radio. It is recommended not to shut the 5GHz radio, so I didn't, but I reduced its power.
I don't have the gateway placed in a great location, but I still get 200 down, 5-10 up. Which is all I need for backup internet.
