No Band N77 on RM502q-AE with ATT Firstnet

Band N77 is in strong within my area, but I cannot connect to it.
My phone with the same sim will connect to B14 and N77 together, so it is expected behavior.

Using NSA mode, I am successfully connecting to B14 and it is doing aggregate connections with B2 and B66, but no 5g bands.
Disabling B14 and B66 lets the modem connect to B2, and it does aggregate connections with B5 and N5.
I can not find a combination of settings and band lockouts to connect to N77.

With my sim inserted, using AT+QSCAN=2 responds with “OK”. Without the sim inserted, it responds with multiple 5g networks. Are there any settings I have missed on the modem?

Dear @BagicBouse
Please check if the conbination support or not by RM520Q-AE.
I have sent the ENDC list to you via Message, please check.