+QMTCONN: 0,0,2 Connection Refused: Identifier Rejected

IoT Modules LTE Standard Module
1

I’m using a Quectel EC200 GSM/4G module and trying to connect to my MQTT broker.

  • The MQTT socket opens successfully (AT+QMTOPEN works fine).
  • But when I send the connect command (AT+QMTCONN), the broker rejects the connection with:
    +QMTCONN: 0,0,2

which according to this document means MQTT Application

Connection Refused: Identifier Rejected

I also have a Quectel M95 (2G) module, and with the same command sequence and same broker, the connection works without issues.

Since the AT command set for MQTT is basically the same between M95 and EC200, I expected the EC200 to work too. But it fails only at the connection stage

What could be the Issue, I will be grateful for any help, Thanks.

2

hi May I ask which module you are currently using? Is it the EC200U?ould you provide the AT log?