EC21 MQTT can't release client identifier

Technical Subjects
1

Hello,
I am using EC21 and MQTT AT command
when MQTT Connection can’t establish to broker, then mqtt client identifier didn’t released

AT+QMTCONN?
+QMTCONN: 0,0

in QMTT Application note, the state is 1 to 4, but EC21 responsed 0.
I tried to send Disconnect and Close At Command but they always reply ERROR
Then I can’t use that client identifier, and I must do a reboot

AT+QMTDISC=0
ERROR
AT+QMTCLOSE=0
ERROR

Why did EC21 reply an unknown state? and how to resolve this issue?

2

Can you provide a complete AT log?

3

Hi @herbert.pan-Q ,
pls see them below:

AT+QMTCONN?
+QMTCONN: 0,0

OK
AT+QMTDISC=0
ERROR
AT+QMTCLOSE=0
ERROR
AT+QMTCONN?
+QMTCONN: 0,0

OK
AT+QMTCONN?
+QMTCONN: 0,0

OK
AT+QMTCONN?
+QMTCONN: 0,0

OK
AT+QMTCONN?
+QMTCONN: 0,0

OK
AT+QFLST="m_ca_root.pem"
+QFLST: "m_ca_root.pem",1187

OK
AT+QFOPEN?
OK
AT+QFDEL="m_ca_root.pem"
OK
AT+QFOPEN="m_ca_root.pem",0
+QFOPEN: 4

OK
AT+QFWRITE=4,1187,5
CONNECT
+QFWRITE: 1187,1187

OK
AT+QFCLOSE=4
OK
AT+QSSLCFG="cacert",5,"m_ca_root.pem"
OK
AT+QSSLCFG="sslversion",5,4
OK
AT+QSSLCFG="seclevel",5,1
OK
AT+QSSLCFG="session_cache",5,0
OK
AT+QSSLCFG="ciphersuite",5,0xFFFF
OK
AT+QSSLCFG="ignorelocaltime",5,1
OK
AT+QMTCFG="ssl",0,1,5
ERROR
4

Hi @herbert.pan-Q
any idea?
I need to fix it soon