nRF9160 modem stuck in "searching" after several successful LTE-M connections

Hello,

If I try to repeatedly connect and then disconnect from the LTE-M network with an nRF9160 (I'm using the Actinius Icarus v2 board), I observe that the first 30 (approx) connection attempts are successful, after which the modem gets stuck in searching mode in future attempts. I think the issue is related to the modem firmware and not the network provider because the connection attempts succeed again if I reset the board altogether.

The following are the sequences of AT commands I used. I suspected the modem reset loop restriction but this should have triggered after the first 5 connection attempts already. Besides, I am always deinitialising the modem with AT+CFUN=0 before attempting another connection, so ideally, the reset loop should not trigger at all.

Device info:

AT%HWVERSION
%HWVERSION: nRF9160 SICA B1A
OK
AT+CGMR
mfw_nrf9160_1.2.3
OK

Successful connection followed by modem power off:

AT%XSYSTEMMODE=1,0,1,0
OK
AT+CEREG=5
OK
AT+CSCON=1
OK
AT+CFUN=0
OK
AT+CMEE=1
OK
AT+CNEC=24
OK
AT+CPSMS=1,,,"00110000","01000001"
OK
AT+CEDRXS=2,4,"1001"
OK
AT+CEREG=5
OK
AT+CSCON=1
OK
AT+CFUN=21
OK
+CEREG: 2,"63A9","01A93900",7,0,0,"11100000","11100000"
+CSCON: 1
+CNEC_ESM: 50,0
+CEREG: 5,"63A9","01A93900",7,,,"00100110","00110000"
+CEDRXP: 4,"1001","1001","0001"
+CSCON: 0
AT+CFUN=0
+CSCON: 1
+CEREG: 0,"63A9","01A93900",7,0,0,"11100000","11100000"
+CSCON: 0
OK

Failed connection followed by modem power off:

AT%XSYSTEMMODE=1,0,1,0
OK
AT+CEREG=5
OK
AT+CSCON=1
OK
AT+CFUN=0
OK
AT+CMEE=1
OK
AT+CNEC=24
OK
AT+CPSMS=1,,,"00110000","01000001"
OK
AT+CEDRXS=2,4,"1001"
OK
AT+CEREG=5
OK
AT+CSCON=1
OK
AT+CFUN=21
OK
+CEREG: 2,"63A9","01A93900",7,0,0,"11100000","11100000"
AT+CFUN=0
+CEREG: 0,"63A9","01A93900",7,0,0,"11100000","11100000"
OK

In the case for failed connection attempt, I do not receive any notifications after +CEREG: 2 (searching for network).

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