Thanks for the detailed post regarding your device not connecting to the 4G network in Boston. It's a bummer that the SIM swap didn't help. Do you by chance have a known working T-Mobile device to test your SIM in to see if it functions? As much as we try, not all device will be compatible with our network. Non-T-Mobile phone & software disclaimer
One last thing I wanted to mention when looking at the Boston area -- we have a good amount of modernization going on which is set to be completed near the end of January of next year. This could be why you're experiencing this only in Boston.
Amanda posted a great response. Have you had the chance to look at her suggestions? Please give us a reply back and let us know. Thank you.