EG25 Azure IoThub MQTT connection issue +QMTOPEN: 0,4

IoT Modules LTE Standard Module
1

Hi support team,

I am using EG25 / EC25 module for the MQTT connection with the Azure IoT hub service

Firmware version - EG25GGDR07A08M2G
Hardware version - EG25-G(D)

Authentication method id SAS token ( Symmetric key authentication )

Communication with DPS was successful and we received the device ID and assigned IoT hub details from the DPS

Issue :

  1. When we tried to connect with the IOT hub then we are getting error in AT+QMTOPEN command. Even if we repeat the following command sequence we are getting same result as +QMTOPEN: 0,4
  2. +QMTOPEN: 0,4 indicates “Failed to parse domain name”
  3. But With MQTT fx there is no issue in connecting with Azure IoT hub. refer following details
  4. PC with MQTT fx and device are at same location

MQTT FX log

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EG25 module log :

[2023-07-21T12:49:18Z] Wrote To Cell: [AT+QMTOPEN=0,“indoreofficeiothub.azure-devices.net”,8883]
[2023-07-21T12:49:18Z] Read from Cell: [OK]
[2023-07-21T12:49:18Z] Read from Cell: [+QMTOPEN: 0,4]

[2023-07-21T12:49:18Z] Wrote To Cell: [AT+QMTOPEN=0,“indoreofficeiothub.azure-devices.net”,8883]
[2023-07-21T12:49:18Z] Read from Cell: [OK]
[2023-07-21T12:49:19Z] Read from Cell: [+QMTOPEN: 0,4]

[2023-07-21T12:49:19Z] Wrote To Cell: [AT+QMTOPEN=0,“indoreofficeiothub.azure-devices.net”,8883]
[2023-07-21T12:49:19Z] Read from Cell: [OK]
[2023-07-21T12:49:19Z] Read from Cell: [+QMTOPEN: 0,4]

[2023-07-21T12:49:19Z] Wrote To Cell: [AT+QMTOPEN=0,“indoreofficeiothub.azure-devices.net”,8883]
[2023-07-21T12:49:19Z] Read from Cell: [OK]
[2023-07-21T12:49:20Z] Read from Cell: [+QMTOPEN: 0,4]

[2023-07-21T12:49:20Z] Wrote To Cell: [AT+QMTOPEN=0,“indoreofficeiothub.azure-devices.net”,8883]
[2023-07-21T12:49:20Z] Read from Cell: [OK]
[2023-07-21T12:49:20Z] Read from Cell: [+QMTOPEN: 0,4]

@lyman-Q
@herbert.pan-Q
@Stephen.Li-Q

2

Hi @gaurav.patni
Judging from the error code, the DNS domain name resolution failed. You can use the AT+QIDNSCFG=[,[,]] command to configure a common DNS server to try.

3

Are you sure about using AT+QIDNSCFG command ?
As same module is working with the other IoT hub . Why it is happening that it is able to resolve DNS of one IoT hub and not other . Note that both Iot hub are successfully connected with MQTT.fx
Could you please review once again ?

Also let us know what need to added in AT+QIDNSCFG = i.e. pridnsaddr and secdnsaddr ?

4

Hi @gaurav.patni
Do you mean that multiple modules work together at the same time, and one of the modules connects to MQTT abnormally, while the other modules connect normally?

5

@lyman-Q
No
We are testing on only one module
Firmware version - EG25GGDR07A08M2G
Hardware version - EG25-G(D)

With the same code , exact same AT command works ok ( connect with MQTT Broker ) for one IoT hub but gives error always with another Iot hub connection +QMTOPEN: 0,4 hence I am doubtful that how AT+QIDNSCFG command will help