We are currently working with the Quectel EG91-NAX module running the following firmware:

IoT Modules LTE Standard Module
,
1

We are currently working with the Quectel EG91-NAX module running the following firmware:

EG91NAXDGAR07A01M1G_01.001.01.001

During our testing, we observed that when the QMI service is stopped or restarted, the GNSS/GPS data output stops or becomes unresponsive until the module is fully power‑cycled. We would like to confirm whether this behavior is:

  1. A known issue in this firmware version
  2. Expected behavior due to internal subsystem interactions
  3. Already addressed in a newer firmware release
  4. Related to any specific configuration or command sequence

Could you please provide the following information:

• Whether this firmware version has any known GPS/QMI interaction issues
• Any recommended firmware update or patch that resolves this behavior
• Best‑practice guidelines for stopping or restarting QMI without impacting GNSS
• Any diagnostic commands or logs you would like us to collect for further analysis

We are happy to provide additional logs, AT command traces, or reproduce the issue if needed.

2

Hi @Kako_Patel

I hope you are doing well.

Thank you for reaching out and for providing detailed information regarding your testing with the EG91-NAX module.

Please find our responses to your queries below:

  1. Whether this firmware version has any known GPS/QMI interaction issues

This is not a known issue in the firmware version currently used.

  1. Expected behavior due to internal subsystem interactions

The EG91 series supports independent GNSS operation, which can function without network assistance (standalone mode).

However, both the QMI (RmNet) data service and GNSS NMEA output typically share the same physical USB interface.

By default, GNSS NMEA sentences are output via the usbnmea port. If your QMI service restart involves resetting the module’s USB interfaces or reloading host-side drivers

(such as qmi_wwan_q), this may cause the NMEA port to disconnect or become unresponsive.

  1. Any recommended firmware update or patch that resolves this behavior

Please check your email for the firmware version.

  1. Best-practice guidelines for stopping or restarting QMI without impacting GNSS

If stopping the QMI service involves an RmNet call teardown, please ensure you are using:

AT$QCRMCALL=0,1

Avoid forcing driver-level resets on the host side, as this may impact other USB endpoints, including GNSS.

  1. Any diagnostic commands or logs for further analysis

Please collect the following for further investigation:

GNSS Status:

  • AT+QGPS?
    Verify whether GNSS remains in the “ON” state (result = 1) after QMI restart

  • AT+QGPSLOC=0
    Check if the module can still acquire a position fix via AT commands

NMEA Output Verification:

  • AT+QGPSCFG=“nmeasrc”,1
    Enable NMEA output via AT port

  • AT+QGPSGNMEA=“GGA”
    Verify if NMEA sentences are still retrievable via AT interface

If NMEA output works via AT commands but not through the usbnmea port, the issue is likely related to USB interface or host driver handling.