EG916 and BG95 MQTT with SSL

Hello!
We have a firmware, that works with a BG95-M3 modem. The firmware uses MQTT with SSL, it connects to our own MQTT broker. Everything works fine with the BG95 modem.
But now we want our device to work with a EG916Q-GL modem. We modified our code, so the modem is able to register in a cellular network and is able to access the Internet.
However, the same MQTT connection sequence does not work for the EG916 modem. Here is the sequence:

AT+QFDEL="*"
OK
AT+QFUPL="tb_ca.pem",2034,60,0
CONNECT
<server certificate>
+QFUPL: 2034,491c
OK
AT+QFUPL="tb_client_key.pem",1674,60,0
CONNECT
<client certificate>
+QFUPL: 1674,3c4f
OK
AT+QFUPL="tb_client_cert.pem",1256,60,0
CONNECT
<client private key>
+QFUPL: 1256,4739
OK
AT+QSSLCFG="cacert",2,"tb_ca.pem"
OK
AT+QSSLCFG="clientcert",2,"tb_client_cert.pem"
OK
AT+QSSLCFG="clientkey",2,"tb_client_key.pem"
OK
AT+QSSLCFG="sslversion",2,3
OK
AT+QSSLCFG="sni",2,1
OK
AT+QSSLCFG="ciphersuite",2,0XFFFF
OK
AT+QMTCFG="version",1,4
OK
AT+QMTCFG="ssl",1,1,2
OK
AT+QMTCFG="timeout",1,10,3,1
OK
AT+QMTCFG="keepalive",1,300
OK
AT+QMTOPEN=1,"<our mqtt broker host>",8883
OK
+QMTOPEN: 1,-1

It works fine for the BG95 modem, and we get +QMTOPEN:1,0.
With the EG916 we are able to connect to some public brokers, for example:

AT+QMTOPEN=1,"broker.hivemq.com",1883
OK
+QMTOPEN: 1,0
AT+QMTCONN=1,"6cbcuj9f3uhddoa11xdj"
OK
+QMTCONN: 1,0,0

The questions are:

  • Are there any differences in MQTT or SSL configuration between BG95 and EG916?
  • What is wrong with our sequence? Why is it working good on the BG95 and not working on the EG916?

(post deleted by author)

Hi! Did you manage to solve the problem?

Hello!
Our company contacted Quectel support, and they were able to help us. They fixed something in the modem firmware and provided us a beta version, so we could verify it. I believe, the fix will be added in a future firmware release.