I ran into that issue last week. I also have T-Mobile home internet (TMHI). I have been able to do any of the online DD stuff with TMHI except online multiplayer matchmaking (ranked, BR, Events, Play with Friends, Online Rated). The only work around I have at the moment is I connect to the hotspot on my phone when I want to play with friends or online competitive and then hop back onto my TMHI whenever I'm doing anything else (to preserve hotspot data). I understand that I do live in the center of a major metropolitan area so if you live in a more rural area this option might not be the most feasible.
This is the best work around that I have right now--I've played 3 online games ranked/Play with Friends games so far using my hotspot and I've had no connectivity or speed issues and it has only taken up 0.53GB worth of usage on my hotspot plan