I’m having trouble using a Quectel RM520N-GL 5G modem with my GL-MT6000 (Flint 2) router.

Routers Cellular, USB modems
1

Environment

  • Router: GL-MT6000 (Flint 2)
  • Firmware: OpenWrt / GL.iNet official firmware
  • Modem: Quectel RM520N-GL
  • Connection: USB 3.0 (M.2 to USB enclosure)
  • SIM tested: LINEMO / Rakuten (Japan)

Problem

The modem is detected by USB, but no WWAN control device is created.

lsusb
Bus 002 Device 006: ID 2c7c:0800 Quectel RM520N-GL

However:

ls /dev/cdc-wdm*
# No such file or directory

Because of this:

  • No QMI / MBIM interface appears
  • Cellular page in LuCI keeps loading / spinning
  • I cannot create a WWAN interface

What I already tried

  • Installed required packages:
    • usb-modeswitch
    • usbutils
    • kmod-usb-net
    • kmod-usb-net-cdc-ncm
    • kmod-usb-net-qmi-wwan
    • kmod-usb-net-cdc-mbim
  • Rebooted the router multiple times
  • Tested with different USB ports and cables
  • Updated the modem firmware to a newer Quectel firmware
  • Checked AT commands (the modem responds normally via USB serial)
  • Tested the same modem on a Windows PC → also not detected as a Cellular modem

SSH log

I have attached a text file containing SSH logs captured while plugging in the modem and attempting to bring up WWAN.

The log includes:

  • dmesg output after connecting the modem
  • lsusb and lsusb -t
  • /dev device enumeration (including missing /dev/cdc-wdm*)
  • Relevant kernel messages related to USB, CDC, QMI, and MBIM

Please let me know if any additional logs or specific debug commands are required.

Questions

  1. Does GL-MT6000 officially support RM520N-GL?
  2. Is there a recommended Quectel firmware for OpenWrt / GL.iNet?
  3. Should AT+QCFG="usbnet" be set to a specific mode (QMI / MBIM)?
  4. Is this more likely a modem firmware issue or a USB descriptor / driver issue?
  5. Are there any additional kernel modules required for this modem?

Any guidance or confirmation would be greatly appreciated.
Thank you very much!
log.zip (18.5 KB)

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2

Hi,

Please see our answers below:

  1. Yes. The MT6000 should support the RM520N-GL by default, with no additional packages required.

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  2. We currently recommend the firmware below, as it has been tested and verified on our side. Please make sure your module is RM520NGLAA (not a different variant).
    RM520N-GL_AA: https://fw.gl-inet.com/download/RM520GL-modem_firmware/RM520NGLAAR03A04M4G_01.202.01.202.zip

  3. Yes — use:
    AT+QCFG="usbnet",0 (set QMI/RMNET mode)

  4. The log indicates the RM520N-GL has been detected and the ttyUSB interfaces are present, so the issue is most likely an incorrect USB networking mode configuration.

  5. No additional kernel modules should be required.