Thanks Zygimantas,
I will check out the cell locking shortly.
In the meantime, I tried to update the modem firmware across an alternative WAN - I get this error. Any guidance? This process now seems to have caused SIM 2 to constantly be showing SIM Card State "Not Inserted".
[ERROR] firmware directory is empty. Mount failed? Exiting...
****
root@Teltonika-RUTX11:~# modem_updater -i 3-1 -v EG06ELAR04A08M4G
[INFO]found modem_n: 0
[000.000]: Version: QFirehose_Linux_Android_V1.4.8
[000.000]: Builded: Dec 30 2022 12:01:23
[000.001]: P: /dev/bus/usb/003/008 idVendor=2c7c idProduct=0306
[000.001]: C: /dev/bus/usb/003/008 bNumInterfaces: 5
[000.001]: I: If#= 0 Alt= 0 #EPs= 2 Cls=ff Sub=ff Prot=ff
[000.001]: E: Ad=81 Atr=02 MxPS= 512 Ivl=0ms
[000.001]: E: Ad=01 Atr=02 MxPS= 512 Ivl=0ms
[000.001]: I: If#= 1 Alt= 0 #EPs= 3 Cls=ff Sub=00 Prot=00
[000.001]: E: Ad=83 Atr=03 MxPS= 10 Ivl=9ms
[000.001]: E: Ad=82 Atr=02 MxPS= 512 Ivl=0ms
[000.001]: E: Ad=02 Atr=02 MxPS= 512 Ivl=0ms
[000.001]: I: If#= 2 Alt= 0 #EPs= 3 Cls=ff Sub=00 Prot=00
[000.001]: E: Ad=85 Atr=03 MxPS= 10 Ivl=9ms
[000.001]: E: Ad=84 Atr=02 MxPS= 512 Ivl=0ms
[000.001]: E: Ad=03 Atr=02 MxPS= 512 Ivl=0ms
[000.001]: I: If#= 3 Alt= 0 #EPs= 3 Cls=ff Sub=00 Prot=00
[000.001]: E: Ad=87 Atr=03 MxPS= 10 Ivl=9ms
[000.001]: E: Ad=86 Atr=02 MxPS= 512 Ivl=0ms
[000.001]: E: Ad=04 Atr=02 MxPS= 512 Ivl=0ms
[000.001]: I: If#= 4 Alt= 0 #EPs= 3 Cls=ff Sub=ff Prot=ff
[000.002]: tmp=/sys/bus/usb/devices/usb3/../driver, driver=../../../../../..
/bus/platform/drivers/xhci-hcd
[000.002]: qusb_noblock_open port_name = /dev/ttyUSB0
[000.004]: old software version: EG06ELAR04A04M4G
[001.005]: poll_wait events=POLLIN msec=1000 timeout
[001.005]: switch to 'Emergency download mode'
[001.007]: successful, wait module reboot
[ERROR] firmware directory is empty. Mount failed? Exiting...
[INFO] retarting modem 0
[INFO] Starting services: