I have a working 1921 router with an AT&T hwic and a Verizon hwic.
Both have active SIMs and I am able to connect with no issues.
I purchased additional router modules for both Verizon and AT&T.
According to my Telco Admin group I should be able to move the SIMs between modules with no problem.
The issue is I can't do that. With either module, Verizon or AT&T, it never connects back to the cell network.
I have verified firmware on each card is identical, but am at a loss on what to try next.