We have really bad service with att in our Carver Langston home, too. Wifi calling is a savior.

Att briefed our ANC bout a year ago, and showed a heat map of their signal strength. Was surprisingly spotty for such an urban, relatively flat area. But cause their antennas are so low, there's lots of attenuation from low hills and masonry buildings.

Also, whoever flipped my house used chicken wire behind the drywall for some reason. So I'm sure that adds some faraday shielding as well.