LB1120 Not connecting to a cell tower

[Dop88]

I purchased the NETGEAR 4G LTE Broadband Modem LB1120 along with a TP-LINK WiFi Router AC1750 to access a 4g LTE tower that is in visual distance of my location. I will be using it in a rural area and accessing it periodically. The tower as far as I know services AT&T, US Cellular, Sprint and possibly T- mobile. I have Verizon as my cell service and only get 1x. I have teathered off others cells and been successful which gave my the available 4g LTE services for that tower. The signal is strong as I stated on cell phones. The tower is visable probably less than a half mile away. My problem is I have tried sims from T mobile, AT&T and US Cellular. They connect at the local store before I leave but when I get to the location none have worked. Solid amber light on LED. The sims are monthly pay as you go data only. Is there something else I should be doing?

[terryal]

We have had great access for two years, but this summer, we have had access issues sporadically (every 2 weeks).  Nothing appears amiss, but the amber light remains, then suddenly turns back to green (3 - 4 bars strength).  I see you have not received any suggestions so far.  We will be monitoring your activity.  Have you received any feedback from the seller? Do you have any suggestions for us? Thank you.

[Dop88]

Thanks for replying. Have not resolved the issue or received any direction on this. I will be back at that location within a few weeks. Just wondering does a cell phone have a better ability for reception than the modem. If so I may need an external antenna. As I stated the cell tower is in visual distance probably less than a 1/2 mile away. Sits on top of a mountain.

[Dop88]

Just adding cell phones get a solid 4g LTE signal.

[LlamaLarry]

That is weird that none of the carrier SIMs are working.  Does the SIM information appear correct in the webui (Settings -> Mobile)?

Any chance you're not seating the SIM properly and/or have the wrong size so it is misaligned?  

I have both an LB1120 and an LB2120 and both were able to connec to AT&T LTE indoors without an antenna. 

[Dop88]

Thanks for replying. Not sure the steps to your first question. I had AT&T and T mobile insert the sims at their stores to make sure they linked up which they did. Never took them out, when I arrived at location they wouldn't link up. Just got the amber light which I let set several miinutes to see if it would complete the link up. Didn't happen. I don't know if the data only cards is the issue.