AT#SSLSECDATA=1,0,2,1704 gives ERROR

I am trying to get MQTT running with SSL (client verification) to

I’ve issued AT#SSLCFG=1,0,2 and received OK.
I have sent the CA and Server certificate using AT#SSLSECDATA=1,1,1,LEN and AT#SSLSECDATA=1,1,0,LEN and received OK for those. I have issued AT#SSLSECDATA=1,0,2 (delete private key) and received OK.

When I try to send the private key which was signed by using AT#SSLSECDATA=1,1,2,LEN I get ERROR back. I’ve looked at a hex dump of the key and it is a properly formatted PEM file (I can decode it) and the length is correct. What could cause the ERROR? Is there something special about writing the key vs writing the certificates? I have not specified a password when writing and it says it defaults to the empty string.

Any suggestions?


Could you please indicate FW and model in use, by sending :