LB1120 Connection Issues

My LB1120 has been working great for my OTR Mobile connection on AT&T network. Occasionally it will bounce from LTE to 3G. I used to be able to go into the network settings on the netgear iOS app and “force” the band to LTE and it would switch. Ever since the most recent firmware update, I cannot do this any longer. Now it is stuck in 3G and will not connect to the network at all. I have tried reboots, factory reset, remove and replace SIM card - all to no change. Any ideas?