Pro1X settings for Mint/T-Mo?

[Motoman 2]

So...I was one of the lucky few that got a Pro1X right away when they first started shipping...like 2 years ago I think.  Problem for me was that, despite assurances from F(X)Tec, it turned out that the device didn't really work with Verizon.  Between being promised that there'd be a new antenna revision, to "no it's just software and we'll fix it," etc. I never actually used the device.

 

Fast forward to now, the phone I have been using is starting to get a bit wonky, so decided to try the Pro1X again.  Granted...there's been no updates to it, and therefore it still won't work with Verizon - but I flashed it to Lineage to get a current version of software on it, and got a SIM card to test with from Mint Mobile - on the T-Mobile network.

The problem being that it just doesn't connect well and actually hold a connection.  So I'm wondering if anyone has any particular settings, like for the APN, that work well with a T-Mo network...or any other advice?