problem getting unlocked mr1100 to connect att

[MVS2]

Trying out a new internet reseller and wanting to use router #2 with that reseller.

Details: 

Reseller #1 :  Sent router #1 with ATT SIM card installed.  Works fine.

Reseller #2:  Allows BYOD, sent SIM card with their logo (not ATT)

Router #1 - MR1100 -  on start up shows the ATT logo, assume is an ATT version

Router #2 - MR1100 -  bought from Amazon, "unlocked" per the listing.  

After login to admin, every single setting and check box is set to exactly the same on both routers

Router #1 will connect to LTE with either SIM card

Router #2 will not connect with either SIM

Trying out a new internet reseller and wanting to use router #2 with that reseller.

Is there something else I can try or is this a bad router?

Thanks

[W1lliam]

What model is this router#2? you can check on the back label after removed the battery and back cover, not every M1 (aka MR1100) model supports all the LTE bands in every country.