We got some problems with NB-IoT connection.
Basically it works but with these issues:
1. NB only doesn't have any effect - In UI, SIM1 is set to 4G(LTE) only and Network Category to NB only, but it still tries to connect to 2G network, which is not allowed on this SIM card and refused - confirmed by the network operator.
This means, that modem scans for Cat-NB1, Cat-M1 and GSM in this order.
2. NB-IoT disconnects regularly and then tries to connect to GSM network. According to operator the all the disconnects have the same scenario:
- attach request - Modem->Network
- authentication request - Network->Modem
- no response from Modem
Modem FW version is: BG96MAR02A07M1G
Is there any newer modem FW version? Can it be upgraded?