So my 5G UC seemed very slow to load any pages in any apps. I ran speed tests and was getting great speed results. However, using apps didn't match the reported speeds that I should be getting. If that seems the case for you then this should fix it.
Go into device settings. Then connections. Then SIM card manager. Turn off your active SIM and wait about 10 seconds. Turn that SIM back on.
Now your device should actually pull those speed test speeds in all your apps.
All you have to do is toggle airplane mode. TMO network is 4G LTE, 5G NR, 5G NSA, and VoLTE on top. 5G NSA USES a 4g LTE fallback for voice and 5G NSA and NR and 4GLTE aren't designed to be deployed they way tmo has so your phone gets stuck In a hand offl oop snd the modem disconnects
Had 5G UC yesterday in Los Angeles. Did a speed test. 550 megabits per second. I was pretty impressed. I don't know if that's any different than when I'm near a Sprint 5G high band Tower. I have t-mobile.