I was able to get a log where AT+CSQ return 99,99 for 5 minutes. Then I restart the modem and I get 11,99 in few second. See log:
10:25:09:
RDY
APP RDY
ATV1
OK
ATE1
OK
AT+CSQ
+CSQ: 99,99
OK
AT+QGPS=1
OK
AT+CSQ
+CSQ: 99,99
OK
10:25:20: AT+CSQ
+CSQ: 99,99
OK
10:25:30: AT+CSQ
+CSQ: 99,99
OK
10:25:40: AT+CSQ
+CSQ: 99,99
OK
10:25:50: AT+CSQ
+CSQ: 99,99
OK
10:26:00: AT+CSQ
+CSQ: 99,99
OK
10:26:10: AT+CSQ
+CSQ: 99,99
OK
10:26:20: AT+CSQ
+CSQ: 99,99
OK
10:26:30: AT+CSQ
+CSQ: 99,99
OK
10:26:40: AT+CSQ
+CSQ: 99,99
OK
10:26:50: AT+CSQ
+CSQ: 99,99
OK
10:27:00: AT+CSQ
+CSQ: 99,99
OK
10:27:10: AT+CSQ
+CSQ: 99,99
OK
10:27:20: AT+CSQ
+CSQ: 99,99
OK
10:27:30: AT+CSQ
+CSQ: 99,99
OK
10:27:40: AT+CSQ
+CSQ: 99,99
OK
10:27:50: AT+CSQ
+CSQ: 99,99
OK
10:28:00: AT+CSQ
+CSQ: 99,99
OK
10:28:10: AT+CSQ
+CSQ: 99,99
OK
10:28:20: AT+CSQ
+CSQ: 99,99
OK
10:28:30: AT+CSQ
+CSQ: 99,99
OK
10:28:40: AT+CSQ
+CSQ: 99,99
OK
10:28:50: AT+CSQ
+CSQ: 99,99
OK
10:29:00: AT+CSQ
+CSQ: 99,99
OK
10:29:10: AT+CSQ
+CSQ: 99,99
OK
10:29:20: AT+CSQ
+CSQ: 99,99
OK
10:29:30: AT+CSQ
+CSQ: 99,99
OK
10:29:40: AT+CSQ
+CSQ: 99,99
OK
10:29:50: AT+CSQ
+CSQ: 99,99
OK
10:30:00: AT+CSQ
+CSQ: 99,99
OK
10:30:10: AT+CSQ
+CSQ: 99,99
OK
10:30:20: AT+CSQ
+CSQ: 99,99
OK
10:30:28: AT+GMI
Quectel
OK
NORMAL POWER DOWN
10:30:35:
RDY
10:30:36:
APP RDY
ATV1
OK
ATE1
OK
AT+CSQ
+CSQ: 99,99
OK
AT+QGPS=1
OK
AT+CSQ
+CSQ: 99,99
OK
10:30:46: AT+CSQ
+CSQ: 11,99
OK
AT+QMTDISC=0
OK
AT+QMTCLOSE=0
ERROR
AT+QICSGP=1,1,"myApn","","",1
OK
AT+QFDEL="*"
OK
AT+QFUPL="ca.crt",1432,500
CONNECT
+QFUPL: 1432,1470
OK
AT+QFUPL="client.crt",1322,500
CONNECT
+QFUPL: 1322,421
OK
AT+QFUPL="client.key",1675,500
CONNECT
+QFUPL: 1675,704a
OK
AT+QSSLCFG="cacert",2,"ca.crt"
OK
AT+QSSLCFG="clientcert",2,"client.crt"
OK
AT+QSSLCFG="clientKey",2,"client.key"
OK
AT+QSSLCFG="sslversion",2,4
OK
AT+QSSLCFG="seclevel",2,2
OK
AT+QSSLCFG="ciphersuite",2,0xFFFF
OK
AT+QSSLCFG="sni",2,0
OK
AT+QMTCFG="version",0,4
OK
AT+QMTCFG="keepalive",0,10
OK
AT+QMTCFG="session",0,0
OK
AT+QMTCFG="ssl",0,1,2
OK
AT+QMTCFG="will",0,1,2,0,"will","Disconnected"
OK
AT+QMTOPEN=0,"xx.xx.xx.xx",8883
OK