How to make Q2686RD work on 3G (AT&T)

AT&T did a 2G sundown so basically all radios working on 2G don’t work. I understand that Q2686RD should also work on 3G.
Been trying to make them work and no connection to AT&T antennas.
Is this right or do they only work on 2G?

Q2686RD is a 2G only device, there were Q26 devices which did support 3G but these are all now end of life and not in manufacture any longer.