RM520N-GL periodic WDS session drops every ~2 minutes in QMI/raw_ip mode on Linux
Device Information
Module: Quectel RM520N-GL
Firmware: RM520NGLAAR03A03M4G
Host platform: Linux 6.6.52
Driver: qmi_wwan (raw_ip mode)
Interface: wwan0 (QMI mode, no rmnet)
RAT: LTE Band 3 (FDD 1800 MHz)
Observed Behavior
The QMI WDS data session drops every approximately 2 minutes, regardless of:
Signal quality (RSSI -59 to -65 dBm, RSRP -88 dBm, SNR 2-8 dB — stable throughout)
Network registration (always registered, never drops)
Traffic activity (drops occur with or without active data transfer)
Keepalive pings (25-second ICMP keepalives to 8.8.8.8 do not prevent drops)
Evidence
Signal during disconnect (stable throughout):
13:31:01 QMI=disconnected PING=FAIL | RSSI: ‘-65 dBm’ RSRQ: ‘-10 dB’ RSRP: ‘-88 dBm’ SNR: ‘3.0 dB’
| Registration state: registered Radio interfaces: 1
No AT URC events at disconnect:
AT+CGEREP=2,1 enabled — no +CGEV received at disconnect
AT+CEREG=2 enabled — no +CEREG change at disconnect
Modem receives no network-initiated deactivation notification
qmicli output at disconnect:
[/dev/cdc-wdm0] Connection status: ‘disconnected’
Recovery: Session reconnects automatically in ~5-10 seconds via qmi-connect.sh.
Drop interval: Consistently every 110-130 seconds (approximately 2 minutes).
What We Have Tried
Keepalive ICMP pings every 25 seconds → no effect
AT+QCFG=“urc/ri/other” — read-only (CME ERROR 4), cannot modify
AT+QMAPWAC=1 + AT+QMAP=“MPDN_rule”,0,1,0,0,1 → no effect (rmnet not available)
AT+QNWPREFCFG=“mode_pref”,LTE → modem on LTE, no effect on drops
Confirmed not operator-side: no AT URC, no network deactivation events
Conclusion
This appears to be an internal WDS session inactivity/management timer in the modem
firmware that resets the QMI WDS data session every ~2 minutes, independent of actual
network or signal conditions.
We have seen a similar report (forum post #55247) where Quectel provided a newer
firmware version that resolved WDS session stability issues on RM520N-GL.
Request
Please provide:
The latest stable firmware for RM520N-GL for use in embedded Linux QMI mode
Confirmation whether this is a known issue in RM520NGLAAR03A03M4G
Release notes or changelog for any newer firmware addressing WDS stability