No 4G LTE CF-31 MC7750

Greetings all, I have multiple toughbooks, all CF-31s with MC7750 and 4G SIMs installed.

The MC7750 only connects to 3G, if I hover the mouse over signal strength indicator it brings up a little box showing the strength of various signals. 2G (1x) and 3G (EV) all green but 4G (LTE) shows "Unavailable."

I've checked the antennas, set Black to main, green to AUX.

I've tried flashing multiple firmware, currently running MC7750_03.05.10.13_00_vzw_033.012_000, no luck.

I've checked the bands and selrat:
00, All bands
!SELRAT: 00, Automatic

I tried setting bands and selrat to LTE only, no luck.

I read through the thread below but can't find the answer,
No 4G LTE on CF-19 MK4?
http://forum.notebookreview.com/threads/no-4g-lte-on-cf-19-mk4.790254/

Thanks for reading so far, I'm stumped. Any help appreciated. Mack

 

I am a hardware guy and can't help much with 4G, but welcome to the forum.
2 points for searching first!

 

Thanks, I always try to research before I post.

Another test, I provisioned a new 4g number and SIM, still stuck in 3G

 

Last time that happened to me, it was my carrier that had a different APN for LTE versus their 3G/HSPA service. I had to dig deep through their support incompetence and lack of documentation to fix that, with some serious googling.

 

Might seem like a dumb question, but who's your carrier, and does the 7750 have the right LTE bands?

 

Excellent, yet overlooked point. I think the MC7750 is a Verizon LTE module. (B13?)