EM05-G – USB ports missing / AT and QMI not available after reboot

IoT Modules LTE-A Module
1

Hello,
I have a modem EM05GFA-128-SGNS in the SBC Simatic IOT2050 running on Debian 11 (bullseye)

ATI
Quectel
EM05-G
Revision: EM05GFAR07A07M1G

The modem is detected by lsusb but no AT or QMI/MBIM ports appear by default.

Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 003: ID 10c4:ea60 Silicon Labs CP210x UART Bridge
Bus 003 Device 004: ID 2c7c:030e Quectel Wireless Solutions Co., Ltd. Quectel EM05-G
Bus 003 Device 002: ID 0424:2514 Microchip Technology, Inc. (formerly SMSC) USB 2.0 Hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Current behavior:

  • After boot, only /dev/ttyUSB0 shows up (DIAG-only)
  • AT commands on /dev/ttyUSB0 don’t respond
  • /dev/cdc-wdm* or wwan0 interfaces do not appear
  • NetworkManager does not detect the modem

Workaround:

  • Remove/load kernel modules and register modem ID:

modprobe -r option usb_wwan usbserial
modprobe usb_wwan
modprobe option
echo 2c7c 030e > /sys/bus/usb-serial/drivers/option1/new_id

  • After this, /dev/ttyUSB1..5 appear
  • One port responds to AT commands
  • I can enable QMI mode

Problem:

  • NetworkManager still does not see the modem reliably
  • After reboot, all settings are lost and the modem returns to DIAG-only mode

Questions:

  1. Is this a firmware issue? Can I get a newer firmware, and how do I flash it?
  2. Is there a way to make EM05-G remember USB composition after reboot?
  3. Can this be done fully in Linux, or do I need UART / Windows tools to flash FW?