BG770: AT+QMTOPEN succeeds but AT+QMTCONN fails with QMTSTAT: 0,3

IoT Modules
1

AT+QMTOPEN=0,"xxxxxxxxx.iot.us-west-2.amazonaws.com",8883
seems happy, returns 0,0

But
AT+QMTCONN=0,"yyyyyyyyy"
returns +QMTSTAT: 0,3

Using SSL, and AFAIK the certs are correct:

AT+QFLST
+QFLST: "cacert.pem",1187
+QFLST: "clientcert.pem",1224
+QFLST: "clientkey.pem",1679
OK

Any ideas?

Thanks
-Dave

2

Hi,
Can you show the AT configuration process? In this way, problems can be found better.

  1. Problems Problems may occur in SSL configurations. You can add the following commands:

AT+QSSLCFG=“sni”,< SSL_ctxID> [,<SNI>] //enableServer Name Indication feature

AT+QSSLCFG=“ignorelocaltime”,< SSL_c

txID> [,<ignore_localtime>] //configure whether to ignore certificate validity check for a specified SSL context:

2, you can use the MQTT.FX software to check whether your connection can be properly connected.

3

There are a few commands here that aren’t necessary (the ping), but that I’ve added just to test things along the way

I added your “sni” suggestion at the end :slight_smile:

ATE1
AT+QCCID
AT+QURCCFG="urcport","main"
AT+QCFG="band",f,0,0
AT+QCFG="nwscanseq",00,1
AT+QCFG="iotopmode",2,1
AT+CSQ
AT+CREG=1
AT+CREG?
AT+QPING=5,"8.8.8.8",5,1
AT+QFLST
AT+QFDEL="*"
AT+QFLST
AT+QFUPL="cacert.pem",1187,100
AT+QSSLCFG="cacert",1,"cacert.pem"
AT+QFUPL="clientcert.pem",1224,100
AT+QSSLCFG="clientcert",1,"clientcert.pem"
AT+QFUPL="clientkey.pem",1679,100
AT+QSSLCFG="clientkey",1,"clientkey.pem"
AT+QFLST
AT+QMTCFG="ssl",0,1,2
AT+QSSLCFG="seclevel",2,2
AT+QSSLCFG="sslversion",2,4
AT+QSSLCFG="ciphersuite",2,0XFFFF
AT+QSSLCFG="ignorelocaltime",2,1
AT+QSSLCFG="sni",2
4

More info:
I’m able to get it to work (open, connect, publish, subscribe) using the MQTT X Windows desktop app.
However, using the same data (certs, URL and client ID) I’m NOT able to get AT+QMTCONN to succeed.
It always returns +QMTSTAT: x,3 (where x is the context)

Would it be possible for me to send my certs, connect info, and AT-command sequence to Quectel for you to try?
This should work, but I can’t figure out what part is broken.

Thanks,
-Dave

5

Can you ping through? From the point of view of network configuration, you configure the GSM network, BG770A should not support GSM network. Suspected MQTT connection failure caused by your module not registering with the network.

Do you plan to use the GSM network?