Structured error finding tips needed to analyse connectivity problems

I’m trying to get a KPN connection via LTE-M.
Still no progress in getting a connection.

AT+CEREG? gives as response +CEREG: 3,0
The 0 means that the device is not registered, the MT is not currently searching an operator to register to.
Can I conclude that there is no connectivity, perhaps no coverage or just that the registration doesn’t work?

AT+COPS=1,2,“20408” gives as response +CME ERROR: no network service.
Does this mean that there is no network coverage or that the LTE-M service isn’t available?

AT+CSQ gives as response +CSQ: 99,99

Are there any tips to systematically eliminate problem areas or to pinpoint where the problem is?

For example:
AT+CLAN? if I get a response with the language NL set does that mean that the SIM is working correctly?
AT+USIMSTAT? gives a response 0 that 0: SIM card not present. This is strange and conflicts with SIM language response
AT+CIMI Is the IMSI coming from the SIM or network?
AT+CREG? Did the registration on the network succeed?
etc.

Best regards,

Peter

@pmb_nl

I have tested the KPN AT command sequence on http://support.sodaq.com/sodaq-one/sff/
I was able to connect and send a message.

You can contact KPN about the LTE-M coverage.

Best regards,
Jan

Thanks Jan, I will try the KPN forum.
Still interested in some guidelines that can assist in error finding.

Best regards,

Peter