When connecting using a Windows 10 Home Edition I got this message :
The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer.
While a Windows Pro version did connect immediately ?
Make sure that these 2 service are started.
“IKE and AuthIP IPsec Keying Modules” and “IPsec Policy Agent”
The IKE and AuthIP IPsec Keying Modules service is required to support L2TP/IPsec and IKEv2 tunnels
Both services are disabled by default in the home ed.