I have an LTAP (not the mini), and I've installed the Quectel EPO6-A (US Version) into the "bottom" PCIe slot (the one with the 2 SIM cards wired to it).

I can see the LTE interface under "Interfaces" in Winbox, however I don't see a registration status, and the LTE scanner shows -73 RSSI for AT&T.

I inserted a Sierra MC7455 into the slot, and it connects without issue.

Has anybody gotten an EP06-A to work with an LTAP? What should i try?

Set the APN to
If you using a phone registered sim card
NXTGENPHONE

If it is a data only sim card (hotspot)
Use
Broadband

That is for AT&T