I have a Telus plan, with US roaming option. I am traveling in US alot. I have a Note 20 Ultra 5G U1 from Samsung US. When in US I can only register on Tmobile and I do get 5G data. It won't let me register on ATT or Verizon even though I see the networks, tried in diffrent states and major cities. "Unable to connect try later"
With same sim card in Note20 Ultra "W" variant, canadian one, it wil register on all 3 major networks in US with no issues. In Canada, traveling on 401 from Windor to Montreal I never get 5G data with this device, only LTE+ Telus tech said nothing to do with them, Samsung told me the same. I reseted all network setings, my APN looks ok, Is set on 5G conection.