Windows 10: Windows 11 Unable to Connect using Windows L2TP VPN

Using a Dell Inspiron 5515 with Windows 11 version 21H2 build 22000.918.My Windows 10 computer, as well as my Android smartphone, are both able to connect using L2TP VPN.I am connecting to a Synology DS712+ NASHowever, Windows 11 does not connect and displays the following error message.As I understand, this seems to be a common problem with Windows 11.

:)

 

Error: 788, when connecting to L2TP VPN

Hi there, recently I got this error when connecting to "L2TP/IPSec with certificate" VPN. I'm not sure what cause this.

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

• Adding AssumeUDPEncapsulationContextOnSendRule
• Restarting both IKE and IPSec services
• Allowing both CHAP and MS-CHAP v2
• Reset network connection
• Connect to different provider
• Re-adding VPN settings

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.

***Original title: VPN Error 788***

 

L2TP not connecting on Windows 11 Insider Program

We experience problems with connecting L2TP VPN on a Windows 11 Insider Program workstations. Since the Windows update patch on Tuesday, we managed to solve the VPN connection problems by removing update KB5009543 on Windows 10 and installing update KB5010795 on Windows 11. However we cannot find KB5010795 update for Insider Program workstations. Does anyone know how we can solve this?

Below is the error with L2TP VPN connections:





Thanks!

 

VPN On Windows 8

Has anybody been able to get VPN (L2TP shared key access) working on Windows 8? I cannot get it to work on a coworker's computer at all. We have tried multiple things that I've found online, but none of the fixes appear to work, and there isn't a concrete fix or answer to the problem. Basically it just won't connect at all. It always ends in error code 809. This is Windows 8 Pro x64 that shipped on a Dell laptop. The VPN works perfectly on a Windows 7 machine (multiple ones).