Persistent +QMTPUB: 0,0,2 during AWS OTA - Possible MQTT Stack Buffer Issue

IoT Modules LPWA Module
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1

Hi Quectel Support,

I am facing a recurring issue during AWS OTA updates where AT+QMTPUB consistently returns +QMTPUB: 0,0,2 (Packet transmission failure).

Module Details:

  • Module: [ BG95-M3]
  • Firmware: [BG95M3LAR02A03_A0.206.A0.206]

Issue Summary:

  • Connection Status: The modem reports a successful connection (+QMTCONN: 0,0,0), but every subsequent publish attempt fails with result 2.
  • Unrecoverable: Once this error occurs, it happens randomly during the update and the modem cannot recover without a hard reset.
  • Internal Stack: Even though the connection seems “alive,” the data fails to transmit.

Questions:

  1. Does this specific firmware version have any known issues or bugs regarding the internal MQTT stack buffer?
  2. Why does the modem report an active connection (0,0,0) while failing all transmission attempts?
  3. Is there a way to clear the MQTT buffers or recover the connection without a reboot?
2

Hi @Charan6

Q: Does this specific firmware version have any known issues or bugs regarding the internal MQTT stack buffer?

A: Actually, there is no similar known issue, and due to there is no modem log we didnt know what happened in module side. Is possibel to test with other MQTT server? then to find the issue caused by server or module.

Q: Why does the modem report an active connection (0,0,0) while failing all transmission attempts?

A: Probably limited by server, it can be connect but cannot receive data or comminute with client.

Q: Is there a way to clear the MQTT buffers or recover the connection without a reboot?

A: Just discnnect MQTT connection or AT+CFUN0/AT+CFUN=1.

If issue still happened and blocked your production, Please contact my email(Linkin.WANG@quectel.com), we need module log to analysis.