This one is quite strange. Have you ever experienced this problem of 'not self registration' of SPNs when the service is running under 'Local System'? As we all know, we will need to do a manual registration of SPNs in certain cases but not when the service is running under 'Local System'.
The error is so 'General' and no more information is logged:
"The SQL Server Network Interface library could not register the Service Principal Name (SPN) [ MSSQLSvc/SQL1.Contoso.net:14330 ] for the SQL Server service. Windows return code: 0x200b, state: 15. Failure to register a SPN might cause integrated authentication to use NTLM instead of Kerberos. This is an informational message. Further action is only required if Kerberos authentication is required by authentication policies and if the SPN has not been manually registered."
I verify that the PC has enough permission to write on SPN attribute, but I have no other idea what could be the problem.