I use 912UAG-2HPnD with Cinterion PLS8-E (LTE module inside), ppp-client mode.

After reboot LTE module use only 3G mode with signal -55..-63.

Module go from 3G to LTE mode in ~30-120 minutes after reboot.

How to troubleshoute the reason of this non-LTE long time mode?

(Russia, Megafon)