Just to add this to the overall community thread - I have been having an issue with the newly added band 2 handoffs in my area.
About 2/3 of the sites now have band 2 (10x10) active, added to existing band 4 (20x20) and band 12 (5x5).
Quite often my phone will 'camp' on band 2 as its primary. In most cases, this is not a problem. The issue does arrive when drive to my neighborhood which is one of a few sites that have 'only' band 4 and band 12. In theory, my phone 'should' handoff to my local site, which is ~1300' away.
However, what has been happening, my phone has been holding onto band 2 from further away sites - typically one that is nearly 3 miles away.
Speeds have gone from ~40-60Mbps on band 4+12 to either 0.22Mbps or 'Network Communication Issues'.
Band 2 (2.88 miles away)
Band 4 (1330' away)
I have opened a ticket on this, as service is literally useless unless I cycle my phone through airplane mode, or go indoors.
T-Mobile states that this will take about 3 months for them to resolve, as they have to upgrade the cell site to fix it.