If the issue is only occurring in one location a service request needs to filed. With a service request our engineers come the area where there is an issue and diagnose and correct the problem. T-Force would love to look in to this issue further for you, can you please send us an e-mail to TForce@T-Mobile.com titled Support Community. Please make sure to include your name, mobile #, issue, & contact time. Thank you!
what happens if you go back to the old phone again now?
If that fails too is just the tower is now having problems and bad timing.
If it works ok back in your old phone then your new phone you got is bad and needs replacement.
their 3g and 4g is on the same frequency so I don't think that change made any difference.