5GE is not working on my iPhone

5GE is not working on my iPhone 12 even though I have cellular data and I use only once I’m outside the house. This happened when they change it from 5G to 5Ge. At home, I have AT&T fiber optic service, so there is no problem. I never use the cellular data at home. I hope someone could explain what seems to be the problem because I need to use my phone once I’m outside and it will never connect to the AT&T cellular data.

Thank you