T-Mobile Home Internet is oddly faster with a VPN.
It's over a cellular network, which often has a slower download and faster upload. This implies the bottleneck is in the band (congested tower / network).
Generally speaking, switching to a VPN should make it worse, not better
Yet, the numbers don't lie. I will have great download speeds and normal upload, when using a VPN.
Changing the DNS with or without VPN, doesn't matter, it's always faster with the VPN.