Problem with service in different cities.

So I have changed the screen on a A3 2016, and after the repair (original screen) the phone won't find any service in my hometown, but when I leave for a bigger city the service is no problem.

When I change from 4G auto to 3G auto there is a small chance that it will find the network for a brief period of time.

Anyone else having this problem?

I think it's no problem with the hardware in the phone because it works in bigger cities without problem.

Thanks in advance