$ benou docs

Personal documentation and knowledge base

5G modem (WWAN)

#system #wwan #modemmanager

5G/LTE modem setup — Quectel RM520N-GL on Lenovo T14s.

Hardware

  • Modem: Quectel RM520N-GL
  • Kernel driver: mhi-pci-generic
  • Primary port: wwan0mbim0 (use MBIM, not plain wwan0)
  • ModemManager plugin: quectel
  • Device ID: 1eac:1007

Setup (first time)

1. Install and enable ModemManager

sudo pacman -S modemmanager
sudo systemctl enable --now ModemManager NetworkManager

2. FCC unlock (required — modem won’t come online without this)

The FCC lock is a software lock from Lenovo that prevents the modem from going online until an unlock sequence is sent. Required on Lenovo/Dell/HP laptops.

sudo mkdir -p /etc/ModemManager/fcc-unlock.d
sudo ln -s /usr/share/ModemManager/fcc-unlock.available.d/1eac:1007 \
           /etc/ModemManager/fcc-unlock.d/1eac:1007
sudo systemctl restart ModemManager

3. Verify modem is detected

mmcli -L             # list modems
mmcli -m 0           # details on modem 0
mmcli -m 0 | grep -i state
mmcli -m 0 | grep -i "primary port"

4. Enable modem and configure

sudo mmcli -m 0 --enable
sudo mmcli -m 0 --set-primary-sim-slot=1
sudo mmcli -m 0 --set-preferred-mode="allowed:4g,5g;preferred:5g"

Check SIM info:

mmcli -i 0

5. Create NetworkManager connection

nmcli connection add type gsm ifname wwan0mbim0 con-name sunrise apn internet
nmcli connection up sunrise

6. Verify connection

mmcli -m 0 | grep state       # should show: state: connected
nmcli device status            # should show: wwan0mbim0  gsm  connected

Daily use

  • Connection is managed by NetworkManager, reconnects automatically
  • To bring up manually: nmcli connection up sunrise
  • To check status: nmcli device status
  • To disconnect: nmcli connection down sunrise

Troubleshooting

  • Modem stuck in low-power/locked state → check FCC unlock symlink exists
  • Modem not detected → sudo systemctl restart ModemManager
  • Connection drops → sudo systemctl restart ModemManager NetworkManager
  • Check MM logs: journalctl -u ModemManager -f
  • Check connection logs: journalctl -xe NM_DEVICE=wwan0mbim0
  • lsmod | grep -E 'qmi_wwan|cdc_mbim' — verify kernel modules loaded
← back to docs