Я обнаружил проблему, это правильный код для подключения MQTT и TLS модуля BG96 к Amazon AWS:
AT+QICSGP=1,1,"Your APN"
OK
AT+QICSGP=1
+QICSGP: 1,"wap.tim.it","","",1
OK
AT+QIACT=1
OK
AT+QIACT?
+QIACT: 1,1,1,"***.***.***.***"
OK
AT+QMTCFG="SSL", 1, 1, 1
OK
AT+QSSLCFG="cacert",1,"ufs:cacert.pem"
OK
AT+QSSLCFG="clientcert",1,"ufs:clientcert.pem"
OK
AT+QSSLCFG="clientkey",1,"ufs:clientkey.pem"
OK
AT+QSSLCFG="sslversion",1,4
OK
AT+QSSLCFG="seclevel",1,2
OK
AT+QSSLCFG="ciphersuite",1,0xFFFF
OK
AT+QSSLCFG="ignorelocaltime",1
+QSSLCFG: "ignorelocaltime",1,1
AT+QMTOPEN=1,"*********.iot.us-east-2.amazonaws.com",8883
OK
+QMTOPEN: 1,0
AT+QMTCONN=1,"YOUR_THING_NAME"
OK
+QMTCONN: 1,0,0
AT+QMTSUB=1,1,"YOUR_TOPIC",1
OK
+QMTSUB: 1,1,0,1
AT+QMTPUBEX=1,1,1,0,"YOUR_TOPIC","TEXT_TO_PUBLISH"
OK
+QMTPUB: 1,1,0