Poor reception help

Have noticed when on the road to my home town,  I get lousy to no cell reception (4 bars 1x in top corner).  

My dad has AT&T service for his iphone and has 4 bars & LTE--- me nothing.  

what can I do in settings so can fix this issue.  Horrible to be on the road for 2 hours and have no cell for big chunk of it.  

I have an Iphone XR and yes I make sure it is up to date on OS & apps.