Error: 788, when connecting to L2TP VPN

[Guest Syafi'i Azami]

Hi, recently I got this error when connecting to "L2TP/IPSec with certificate" VPN with Windows 10. I'm not sure what cause this since my friend can connect to it normally using same configuration and same routers.

 

I have already follow some of this steps with no luck :

 

• Adding AssumeUDPEncapsulationContextOnSendRule
  
• Restarting both IKA and IPSec services
  
• Allowing both CHAP and MS-CHAP v2
  
• Reset network connection
  
• Connect to different provider
  
• Re-adding VPN settings
  
• Allowing 500, 4500 in the inbound and outbound firewall rule
  
• Disable firewall
  

 

There also little bit information can be found in the event viewer :

 

 

CoId={AEE0E2A8-34DF-41BB-B5F0-0458EFD41751}: The user xxx\xxx has started dialing a VPN connection using a per-user connection profile named yes. The connection settings are:

Dial-in User = *\

VpnStrategy = L2TP

DataEncryption = Requested

PrerequisiteEntry =

AutoLogon = No

UseRasCredentials = Yes

Authentication Type = PAP

Ipv4DefaultGateway = Yes

Ipv4AddressAssignment = By Server

Ipv4DNSServerAssignment = By Server

Ipv6DefaultGateway = Yes

Ipv6AddressAssignment = By Server

Ipv6DNSServerAssignment = By Server

IpDnsFlags =

IpNBTEnabled = Yes

UseFlags = Private Connection

ConnectOnWinlogon = No

IPsec authentication for L2TP = Machine certificate.

 

 

CoId={AEE0E2A8-34DF-41BB-B5F0-0458EFD41751}: The user xxx\xxx is trying to establish a link to the Remote Access Server for the connection named yes using the following device:

Server address/Phone Number = xxx.xxx.xxx.xxx

Device = WAN Miniport (L2TP)

Port = VPN3-1

MediaType = VPN.

 

 

CoId={AEE0E2A8-34DF-41BB-B5F0-0458EFD41751}: The user xxx\xxx dialed a connection named yes which has failed. The error code returned on failure is 788.

 

 

I was wondering if some apps probably causing this error, but i have no idea which one.

 

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