Troubleshooting the SSL Web Client sketch

[boriskogan81]

I am using a MKR1400 with an activated Arduino SIM and trying to set up a basic HTTP SSL connection over GSM. I'm using the example web client sketch found here: https://www.arduino.cc/en/Tutorial/MKRGSMExamplesSSLWebClient

I get this output:

OK
AT+USECPRF=0,0,1

OK
AT+USOCO=0,"arduino.cc",443

ERROR
AT+USOCL=0

ERROR
connection failed

+UUSOCL: 0

disconnecting.

How do I troubleshoot/debug this?