I deactivated my SIMs and activated them again, but they are not workingYou will have to clear the FPLMN list on the SIM.
When a SIM suddenly drops offline, what can we do besides restarting the device?Having Fallback strategies ensures higher uptime
Signaling Logs / Network Logs are empty.Make sure that device settings are correct and test connectivity with AT commands.
Why is my device connecting to 4G and GSM simultaneously?Your device is connecting to two different sides of the network for different purposes.
Unusual blocking of LTE-M and NB-IoT by certain carriersA couple of networks are closing LTE-M connections after they are created as a way to reject LTE-M.