5g home internet problem

I've had basically the opposite experience here.

In my location, Verizon is suffering from the overcongested backhauls that bring data to it's knees except in the wee hours of the morning.  T-Mobile came to the rescue.  That being said, a T-Mobile test drive hotspot or a smartphone get priority data.  A hotspot, internet gateway, tablet, or anything using a phone's hotspot get throttled during busy times of day when the network can't handle the traffic.  

My Samsung phone runs ok as a desktop device however when I connect it to a dock and use a monitor, keyboard, and mouse.

T-Mobile support gets better if you work your way up through their "tiers".  When I initially started using T-Mobile and was rightfully offended by the fact their test drive trial device gave me better service than what I got after I signed up, I eventually got connected to a really helpful higher tier support agent that was able to really pull some strings and get things done.  We worked together for about a month.