Poor LTE signal due to incorrect band on N910U

I got an N910U for use on AT&T in the US. All the phones in my house get full bars since I am on a hill near a lot of cell towers. Except the N910U usually has 0 to 1 bars and only rarely gets LTE. I used LTE discovery app to see that it is almost always on band 2 where the signal is very poor, but very ocassionally switches to band 17 and gets full bars! Then it quickly switches back to band 2 and gets 0 or 1 bars. I tried flashing the other two modems I could find, but it did not change how it acted. I am about to send it back for a refund and get an N910T instead to see if that works better, but it would be much easier to find a solution to why it won't use the strongest signal,