Hello team and community,
Since updating my RUTC router firmware and modem firmware, the internal modem has become completely unstable and can no longer establish a mobile connection.
Device: RUTC
Router Firmware: Initially upgraded to RUTC_R_00.07.20.3 (stable), later also tried RUTC_R_00.07.21.2
Modem: Quectel (USB ID 2c7c:080.1)
Modem Firmware: RG520NEBDCR03A05M4G
Carrier: Telekom Deutschland (), 5G-NSA
SIM: Single SIM in slot 1, PIN enabled
Problem
After upgrading to router firmware RUTC_R_00.07.20.3 (stable) including a modem firmware update to RG520NEBDCR03A05M4G, the internal modem has become unstable. The issue first appeared sporadically (SIM briefly detected as “not inserted”) and has since become permanent. The mobile connection can no longer be established.
As i write I have also tried upgrading to RUTC_R_00.07.21.2. The problem persists on both router firmware versions. Could the modem firmware RG520NEBDCR03A05M4G be the cause?
Before the update, the modem was running stable on 5G-NSA (Telekom).
A very similar issue has been reported here: RUTX50 internal modem unstable after modem firmware update or RUTC50 Modem issue since Update - Mobile 5GMM reject cause: N1 mode not allowed
Symptoms
- SIM detected as “not inserted” despite being physically seated correctly
- PIN state flipping spontaneously between
OK (1)andRequired PIN (4), multiple times within seconds - AT commands failing across the board with “Failed to parse response”, “Request timed out” and “Invalid response”
- Modem not registering on any network (all xREG statuses: “Not registered”)
- APN lost after reboot. APN was empty, manually configured APNs are not processed correctly by the modem
- Router crashed: “Device startup after unexpected shutdown” immediately following the SIM loss event
- SMS storage check failing in an endless loop (
mb_check_sms_storage:564)
Syslog error messages
daemon.err mobifd: [gsm.modem0] GSM error in "mb_check_sms_storage:564" (Failed to parse response)
daemon.err mobifd: [gsm.modem0] GSM error in "get_ip_address_form_pdp_cb:108" (Failed to parse response)
daemon.err mobifd: [gsm.modem0] GSM error in "check_modem_attachment:77" (Failed to parse response)
daemon.err mobifd: [gsm.modem0] GSM error in "validate_and_set_sim_hotswap:57" (Request timed out)
daemon.err mobifd: [gsm.modem0] GSM error in "generic_clip_cb:1078" (Invalid response)
daemon.info mobifd: [gsm.modem0] APN "" isn't prepared for PDP "1", preparing it
daemon.info gsmd: PIN State changed to: Required PIN (4) — flipping repeatedly
What I have already tried
- Removed SIM card, cleaned contacts, reinserted
- Manually set correct APN (
internet.telekom) - Entered SIM PIN in the WebUI
- Changed SIM card and network configuration multiple times
- Modem restart via WebUI
- Factory Rese
- Full router reboot
- Tried both router firmware versions (RUTC_R_00.07.20.3 stable and RUTC_R_00.07.21.2). Issue persists on both
Questions
- Is this a known issue with modem firmware RG520NEBDCR03A05M4G?
- Is it possible to downgrade the modem firmware to the previous version?
- Is there a newer modem firmware version available for the RUTC?
I am currently without mobile connectivity and need help resolving this as soon as possible. I can provide the full syslog and a troubleshoot file if needed.
I can provide the full syslog and a troubleshoot file if needed.
Thanks in advance!