Mqtt SSL connection issue

Hello Everyone,

  I have followed the documentations and At command sequence and I am facing issue at mqtt-ssl connection. The required response should be according to documentation is `+QMTOPEN: 0,0` but we get `+QMTOPEN: 0,4` I think issue is at uploading certificates.

I have follwed following steps to upload the certificates:

  1. I have used Tera View application for uploading certifiactes
AT+QFUPL="ca1.pem",1184,5000

AT+QFUPL="cert1.pem",1210,5000

AT+QFUPL="key1.pem",1662,5000

by using above command new window opne in tera view. We upload certificate as it is like below:

-----BEGIN CERTIFICATE-----
MIIDWTCCAkGgAwIBAgIUakWX7ICUwRBtgaEgA21Ql3gAefcwDQYJKoZIhvcNAQEL
........
-----END CERTIFICATE-----

I got response like:

Response: AT
OK

Response: ATI
Quectel
EC200U
Revision: EC200UCNAAR03A03M08

OK

Response: AT+CFUN=1
OK

NO: AT+CPIN?
+CME ERROR: 10

Response: AT+CSQ
+CSQ: 20,99

OK

Response: AT+COPS?
+COPS: 0

OK

Response: AT+CGDCONT=1,"IPV4V6","airtelgprs.com"
OK

NO: AT+CGATT=1
+CME ERROR: 50

Response: AT+CGACT=0,1
OK

Response: AT+CGPADDR=1
OK

Response: AT+QMTCFG="recv/mode",0,0,1
OK

Response: AT+QMTCFG="SSL",0,1,0
OK

Response: AT+QMTCFG="pdpcid",0,1
OK

Response: AT+QMTCFG="recv/mode",0,0,1
OK

Response: AT+QMTCFG="keepalive",0,30
OK

Response: AT+QMTCFG="session",0,1
OK

Response: AT+QSSLCFG="cacert",0,"ca1.pem"
OK

Response: AT+QSSLCFG="clientcert",0,"cert1.pem"
OK

Response: AT+QSSLCFG="clientkey",0,"key1.pem"
OK

Response: AT+QSSLCFG="seclevel",0,2
OK

Response: AT+QSSLCFG="sslversion",0,4
OK

Response: AT+QSSLCFG="ciphersuite",0,0xFFFF
OK

Response: AT+QSSLCFG="ignorelocaltime",0,1
OK

Response: AT+QMTCFG="VERSION",0,4
OK

AT+QMTOPEN=0,"a38rhx6jdboq9n-ats.iot.ap-south-1.amazonaws.com",8883
Response: AT+QMTOPEN=0,"-----ats.iot.ap-east-1.amazonaws.com",8883
OK

+QMTOPEN: 0,4

I uploaded certificate by three different ways the ways are as follows:

  1. I directly uploaded the certificate in .pem format.
  2. Also uploaded th certificate in Binary(.der) format.
  3. Also uploaded th certificate with CR/LF format.

for all above methods i have got the same response.

I aslo followed the sequence uploaded on forum:

https://forums.quectel.com/t/quectel-ec200u-mqtt-at-command-qmtopen/17573

The forum contains some command which are not working on my device but the forum device module is similar to my module what is the issue?

Energy-Efficient MQTT Protocol Based Processing Architecture for Water Monitoring Application

refer to this research paper