Issues with RM520N-EU Module: Unreliable Connectivity and PDU Context Activation

Technical Subjects Upgrade/Debug
1

I am using the Quectel RM520N-EU module and encountering several issues during operation. Here are the problems I am facing:

  1. When connecting via the QMI script, the connection is established only about 20% of the time (2 out of 10 attempts). It lacks reliability. At times, the connection fails completely and does not establish at all.
  2. On running the script, the wwan0 interface does not acquire an IP address at all.
  3. When trying to activate the PDU context using the command AT+CGACT=1,1, the command fails, and the context does not activate.

Could you please provide guidance on how to resolve these issues and ensure a more stable connection?

2

Hi Khan,

Glad to see the question!
I am wondering how you use the QMI script for the RM520N-EU? Do you try the quectel-CM.
Do you have any logs about it?

3

HI Bean,
Thank you for your response!

  1. Could you please provide me with the latest version of the Quectel-CM code for Linux and any specific guide to using it with the RM520N-EU module? This would be very helpful.
  2. Regarding the logs, could you kindly specify which logs would be most useful for diagnosing the issue? so that i can share with you.
    Thanks
4

The Quecte ConnectManager

quectel-open-source/Quectel_QConnectManager_Linux: Quectel_QConnectManager_Linux_V1.6.7

5

Hi Khan,

If you start the quectel-CM and provide the log of the quectel-CM, we can see when and why the RM520N lose connection.

6

Thanks alot let me try it please

7

[quote=“Bean.Wang-Q, post:5, topic:42435”]
Hello Bean,
Here are some logs. Let me know if you need any additional information.
[01-09_12:30:40:436] QConnectManager_Linux_V1.6.7
[01-09_12:30:40:437] Find /sys/bus/usb/devices/2-2 idVendor=0x2c7c idProduct=0x801, bus=0x002, dev=0x009
[01-09_12:30:40:437] Auto find qmichannel = /dev/cdc-wdm0
[01-09_12:30:40:437] Auto find usbnet_adapter = wwan0
[01-09_12:30:40:437] netcard driver = qmi_wwan, driver version = 5.15.0-1070-raspi
[01-09_12:30:40:437] unsupport software_interface 1

8

Could you show

1. lsusb -t
2. sudo systemctl status ModemManager
9

/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M
|__ Port 2: Dev 19, If 0, Class=Vendor Specific Class, Driver=option, 5000M
|__ Port 2: Dev 19, If 1, Class=Vendor Specific Class, Driver=option, 5000M
|__ Port 2: Dev 19, If 2, Class=Vendor Specific Class, Driver=option, 5000M
|__ Port 2: Dev 19, If 3, Class=Vendor Specific Class, Driver=option, 5000M
|__ Port 2: Dev 19, If 4, Class=Vendor Specific Class, Driver=qmi_wwan, 5000M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 480M
|__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M

10

Could you check

lsof | grep cdc-wdm

11

For modem manager
● ModemManager.service - Modem Manager
Loaded: loaded (/lib/systemd/system/ModemManager.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2025-01-09 16:53:03 UTC; 15h ago
Main PID: 14060 (ModemManager)
Tasks: 5 (limit: 4915)
Memory: 3.2M
CPU: 50.059s
CGroup: /system.slice/ModemManager.service
├─14060 /usr/sbin/ModemManager
└─14248 /usr/libexec/qmi-proxy

Jan 10 08:41:03 raspberrypi91 ModemManager[14060]: [modem5] simple connect state (4/10): wait to get fully enabled
Jan 10 08:41:03 raspberrypi91 ModemManager[14060]: [modem5] power state updated: on
Jan 10 08:41:03 raspberrypi91 ModemManager[14060]: [modem5] 3GPP registration state changed (unknown → unknown)
Jan 10 08:41:04 raspberrypi91 ModemManager[14060]: [modem5] state changed (enabling → enabled)
Jan 10 08:41:04 raspberrypi91 ModemManager[14060]: [modem5] simple connect state (5/10): wait after enabled
Jan 10 08:41:04 raspberrypi91 ModemManager[14060]: [modem5] simple connect state (6/10): register
Jan 10 08:42:05 raspberrypi91 ModemManager[14060]: [modem5] 3GPP registration state changed (unknown → idle)
Jan 10 08:42:05 raspberrypi91 ModemManager[14060]: [modem5] simple connect started…
Jan 10 08:42:05 raspberrypi91 ModemManager[14060]: [modem5] simple connect state (6/10): register
Jan 10 08:42:05 raspberrypi91 ModemManager[14060]: [modem5] 3GPP registration state changed (idle → unknown)

lsof | grep cdc-wdm
no result

12

ModemManager is running.
If you want to test the quectel-CM, please disable the ModemManager

sudo systemctl stop ModemManager
sudo systemctl disable ModemManager
13

Thank you so much, Bean. The firmware update resolved the issue.