I believe that would be a question for T-Mobile. But if I had to guess, more network congestion for their network since they’re really pushing home internet service sales.
It’s quite curious that a VPN is not resolving the problem. I’m wondering if something isn’t configured correctly. I’m in the Southeast US. If I set a VPN to Sydney, I get placed on the Sydney server.
The IPs for the match servers are not static to protect against DDoS attacks, so I don’t recommend doing that. Only the authentication servers (login process) remain the same.