Windows 10: Cannot connect to L2TP VPN on Windows 11

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Struggling to connect to L2TP VPN on Windows 11? You are not alone. This often occurs because Windows 11 has stricter security settings that can clash with the older L2TP/IPsec protocol. The good news is that this is usually fixable by tweaking some specific settings on the device. In this article, we will walk through […]

This article Cannot connect to L2TP VPN on Windows 11 first appeared on TheWindowsClub.com.

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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***

 

Windows 10 L2TP VPN connection issue

I have a Windows 10 client which has been configured to connect to an L2TP VPN.

To get the connection to work, I had to add the "AssumeUDPEncapsulationContextOnSendRule" registry Key, and then totally disable Windows Firewall—the VPN connects perfectly this way.

However, I cannot get the VPN to connect with the Windows Firewall enabled and I really need to keep the Windows Firewall enabled and be able to connect to the L2TP VPN.

I have also allowed...

• Protocol 50 (ESP) in and out
  
• UDP 1701, 4500, 500 in and out
  

However the VPN still only connects if I totally disable the Windows Firewall and not with it enabled.

Question: Any help or guidance suggested to further troubleshoot this problem?

 

Vpn ( trusted Vpn)

I use Nordvpn. You can connect 6 devices. You can choose servers by country or by a list of each server in each country, use UDP or HTTP, PPtP, L2TP. Double VPN, TOR via VPN. There`s are apps for android and iphones as well as DNS leak protection.