With the module connected, registered and attached to the NB-IoT network, without PSM active, an error occurs after a few (usually 6-7) login - send data - logout actions. The module has the latest firmware.
A detailed list of AT commands and results follows:
AT+CGATT?
<< +CGATT: 1
<< OK
AT+CSQ
<< +CSQ: 16,99
<< OK
AT+CGDCONT?
<< +CGDCONT: 1,“IP”,“APN_address_Edited”,“10.21.1.145”,0,0,0,0
<< OK
AT+UMQTTNV=0
<<
<< +UMQTTNV: 0,1
<< OK
AT+UMQTT=0,“Topic”
<<
<< +UMQTT: 0,1
<< OK
AT+UMQTT=3,“5.196.95.208”,1883
<<
<< +UMQTT: 3,1
<< OK
AT+UMQTT=12,1
<<
<< +UMQTT: 12,1
<< OK
AT+UMQTTC=1
<<
<< +UMQTTC: 1,0
<< OK
MQTT failed
AT+UMQTTC=1
<<
<< +UMQTTC: 1,0
<< OK
MQTT failed
AT+UMQTTER
<<
**<< MQTTER: 350,-20025
<< OK
AT+UMQTTC=0
<<
<< +UMQTTC: 0,0
<< OK
Has anyone encountered the same issue?