Hi,
I have an issue when trying to open TCP connection to MQTT broker via AT+QMTOPEN command. I am using GPRS or eMTC connection depending on our device configuration. When using GPRS technology it works perfectly on every attempt when signal strength is good. When using LTE it generally works but MQTT connection fails every few attempts with DNS parsing error.
Below is my AT command flow:
AT
OK
AT+IPR=115200
OK
ATE0
OK
AT+CTZU=1
OK
AT+CPIN?
+CPIN: READY
OK
AT+QCFG="nwscanseq",02,1
OK
AT+QCFG="nwscanmode",3,1
OK
AT+QCFG="iotopmode",0,1
OK
AT+QCFG="servicedomain",2,1
OK
AT+QCFG="band",0,0x80085,0x80085,1
OK
AT+CGREG=2
OK
AT+CEREG=2
OK
AT+CEREG?
+CEREG: 2,5,"D489","2343E0D",8
OK
AT+COPS?
+COPS: 0,0,"Orange",8
OK
AT+CCLK?
+CCLK: "22/10/03,13:35:28+08
OK
AT+QCSQ
+QCSQ: "eMTC",-81,-112,75,-18
OK
AT+CGDCONT=1,"IP","my_apn"
OK
AT+QIACT?
OK
AT+QIACT=1
OK
AT+QMTCFG="version",0,4
OK
AT+QMTCFG="timeout",0,15,1,0
OK
AT+QMTCFG="session",0,1
OK
AT+QMTOPEN=0,"my_mqtt_broker_address",1883
OK
+QMTOPEN: 0,4 // Failed to parse domain name
Ping after setting APN and activating PDP context also gives error result:
AT+QPING=1,"my_mqtt_broker_address",5,10
OK
+QPING: 565 // DNS parse failed
In our test environment ~80% of connections are successful and data is published without problems. It may be network issue, but first I want to ensure my module configuration before connection is corrent before I send the request to network support.
My module firmware version is BG600LM3LAR02A04.
I found similiar issue for BG95 where module firmware update helped:
May I receive latest firmware for BG600LM3? Maybe this will fix the issue.
Thanks for any help in advance,
Adam