--- Part A ---
A little back story. I was on the $30 prepaid plan. Enjoyed it a lot. I've been a T-Mobile customer for a long time. Recently got a new job and my commute is farther, so I wanted some extra calling time, and I have a few friends that some are on T-Mobile and some weren't.
We moved to T-Mobile ONE with 4 lines.
I popped in the new sim card and after everything was ported went out and tested it the next day.
On the road that I've driven on for a month straight I have had 4G LTE all the way down Now for some reason, the phone will connect to HSPA when driving (or switching towers). And I know this because either:
1. I toggle airplane mode and it then connects to LTE in the same spot. OR
2. I go into the phone information and force LTE Only, the radio then begins to go from H to LTE.
This is very strange, and this did not happen when I was with my prepaid plan. Is there some weird APN settings I have to set? They are all the default fast.t-mobile.com stuff.
I also researched a bit around and seen that there is an issue with Nexus 6P on Android 7.1.1 with T-Mobile: https://code.google.com/p/android/issues/detail?id=232089
However, again, this did not happen with my old sim and prepaid plan, only after switching to T-mobile ONE.
--- Part B ---
One of my buddies that also switched with me is very disappointed in the coverage. All of his data speeds are 1-2Mbps. Places that say "Verified" produce terrible results. The location in question is IBM in Poughkeepsie, NY for example. He also has a Nexus 6P.
This might be related to this thread as well: Why does T-Mobile claim 'verified' 4G LTE service (and actual service) where there is none ?
The coverage map around our area is showered with LTE.
But ever since we switched, at his work or apartment, he has very little service, or it's 1-2Mbps and terrible speeds. He's about to go back to Cricket if this isn't resolved.