QMTOPEN on EC200U modem gives error

IoT Modules LTE Standard Module
1

Hi,

I am bit new to the EC200U module. Have been trying to use MQTT. The QMTOPEN command works intermittently. .Mostly it returns error (QMTOPEN: 1,4) that indicates “Failed to parse domain name”.

Below is the entire command sequence I used…

12-10-2023 16:26:10.386 [TX] - AT+CSQ

12-10-2023 16:26:10.399 [RX] - AT+CSQ

+CSQ: 24,99

OK

12-10-2023 16:26:11.855 [TX] - AT+CPIN=?

12-10-2023 16:26:11.867 [RX] - AT+CPIN=?

OK

12-10-2023 16:26:12.589 [TX] - AT+CREG?

12-10-2023 16:26:12.602 [RX] - AT+CREG?

+CREG: 0,1

OK

12-10-2023 16:26:13.396 [TX] - AT+CEREG?

12-10-2023 16:26:13.408 [RX] - AT+CEREG?

+CEREG: 0,1

OK

12-10-2023 16:26:14.761 [TX] - AT+QICSGP=1,3,“jionet”,“”,“”,1

12-10-2023 16:26:14.775 [RX] - AT+QICSGP=1,3,“jionet”,“”,“”,1

OK

12-10-2023 16:26:17.151 [TX] - AT+QIACT=1

12-10-2023 16:26:17.164 [RX] - AT+QIACT=1

12-10-2023 16:26:20.791 [TX] - AT+QMTOPEN=1,“broker.hivemq.com”,8883

12-10-2023 16:26:25.908 [RX] -
OK
AT+QMTOPEN=1,“broker.hivemq.com”,8883

OK

+QMTOPEN: 1,4

2

Hi @Sanjay_Dalvi
+QMTOPEN: 1,4 means domain name resolution failed. Please confirm whether the domain name is correct. Can other devices access this domain name normally?

3

Forget about MQTT for a while and see if you can establish basic Internet connection, check that you have an IP address, DNS address(es) assigned and you can ping any destination on Internet.
Your domain name is obviously correct and resolvable.

4

Thank you all. The same broker url along with other parameters works very well when connected through MQTTBox client from desktop.

By the way, I discovered that the issue is with a specific carrier (‘ Jio’in India) SIM only. It works perfectly by using another carrier SIM (Vodafone) in India. So wondering what is specific about the Jio network carrier.

I have also contacted the local Quectel representatives here. Hoping to find at least the reason for why it’s not working with the specific carrier.

Thanks again for your reply…