FIX: Windows 10 VPN error 789 connection failed due to security issues

• VPN error 789 appears when a Windows 10 system isn’t configured properly and it is connected to a VPN using the L2TP protocol.
• This error can be fixed with a quick network adapter reset and a certificate check. IPSec configuration should be changed as well as a fallback solution.
• If you are interested in VPN protocols, check out our encryption section on the website to learn more.
• Visit the VPN How-to Guides for articles that instruct you on how to get the most out of your VPN.

If you’re using a VPN, and get prompted with the Windows 10 VPN error 789 that states:

The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer

This error pops up when your system is not properly set up to connect to an L2TP server, thus the connection attempt fails even before you establish a connection with the server.

It is also linked to the incorrect configuration of your operating system like Windows 10 in this case. This generic error is thrown when the IPSec negotiation fails for the L2TP/IPSec connections.

Other possible causes include:

• L2TP based VPN client (or VPN server) is behind NAT.
• Wrong certificate or pre-shared key is set on the VPN server or client
• A machine certificate or trusted root machine certificate is not present on the VPN server.
• Machine Certificate on VPN Server does not have ‘Server Authentication’ as the EKU

Here are solutions you can use to fix Windows 10 VPN error 789 on your computer.

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How do I fix Windows 10 VPN error 789?

Before trying any of these solutions, ensure that L2TP and IPSec pass-through options are enabled from your router. If you configured your VPN service manually, then make sure you use the preshared key 12345678.

Additionally, you should consider changing your VPN provider.

Since you have already encountered errors with your previous service, you will probably be looking for one that is stable and secure and has no compatibility issues with Windows 10.

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1. Reset network adapter

• Right-click Start and select Device Manager

• Identify your network adapter and right-click on it then select Uninstall
• Click OK
• Restart your computer. The device will reinstall and should reset it to default settings

If this doesn’t fix Windows 10 VPN error 789, try the next solution.

2. Check the certificate

Ensure the correct certificate is used both on the client and the server-side. In case Pre Shared Key (PSK) is used, ensure that the same PSK is configured on the client-side, and the VPN server machine.

3. Re-enable IPSec on your computer

• Right-click Start and select Run

• Type services.msc
• Find IKE and AuthIP IPSec Keying Modules

• Find IPSec Policy Agent

• Check the status. If it says started click to restart. If the started option is disabled, enable it
• Double click on each of the two
• Select Startup type

• Change it to Automatic

• Save the changes
• Restart your VPN service

Once you have done all the steps above carefully, the VPN should work smoothly as the protocol settings have been reset to default.

If, however, it doesn’t work, you have to manually set the encryption method both for the server and the client-side , in order for them to be compatible.

In case you have a user-specific issue on your computer yet you still get Windows 10 VPN error 789 after trying any of the above solutions, you can also contact the customer care or tech support team for your specific VPN provider and share the details for further assistance.

Do let us know if any of these solutions fixed the Windows 10 VPN error 789 by leaving a comment in the section below.

Error 789 when connection from Windows 10 #75

Comments

anmiles commented Apr 26, 2018

Error 789: The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer.

Docker image run within ubuntu server (EC2).
Security groups allow any connections between my client and server.
Ports 500 and 4500 are open on the server (udp).
PSK is the same on the client and on the server.
Username and password are double-checked.
One-time registry change is applied on windows.
Both IKEEXT and PolicyAgent services are started on windows.

Here is log (client ip address is changed):

Apr 26 07:23:32 e0de3bb49b45 pluto[2081]: packet from 1.2.3.4:500: ignoring unknown Vendor ID payload [01528bbbc00696121849ab9a1c5b2a5100000001]
Apr 26 07:23:32 e0de3bb49b45 pluto[2081]: «l2tp-psk»[1] 1.2.3.4 #1: responding to Main Mode from unknown peer 1.2.3.4 on port 500
Apr 26 07:23:32 e0de3bb49b45 pluto[2081]: «l2tp-psk»[1] 1.2.3.4 #1: Oakley Transform [AES_CBC (256), HMAC_SHA1, DH20] refused
Apr 26 07:23:32 e0de3bb49b45 pluto[2081]: «l2tp-psk»[1] 1.2.3.4 #1: Oakley Transform [AES_CBC (128), HMAC_SHA1, DH19] refused
Apr 26 07:23:32 e0de3bb49b45 pluto[2081]: «l2tp-psk»[1] 1.2.3.4 #1: STATE_MAIN_R1: sent MR1, expecting MI2
Apr 26 07:23:33 e0de3bb49b45 pluto[2081]: «l2tp-psk»[1] 1.2.3.4 #1: retransmitting in response to duplicate packet; already STATE_MAIN_R1
Apr 26 07:23:34 e0de3bb49b45 pluto[2081]: «l2tp-psk»[1] 1.2.3.4 #1: retransmitting in response to duplicate packet; already STATE_MAIN_R1
Apr 26 07:23:37 e0de3bb49b45 pluto[2081]: «l2tp-psk»[1] 1.2.3.4 #1: retransmitting in response to duplicate packet; already STATE_MAIN_R1
Apr 26 07:24:32 e0de3bb49b45 pluto[2081]: «l2tp-psk»[1] 1.2.3.4 #1: deleting incomplete state after 60.000 seconds
Apr 26 07:24:32 e0de3bb49b45 pluto[2081]: «l2tp-psk»[1] 1.2.3.4 #1: deleting state (STATE_MAIN_R1)
Apr 26 07:24:32 e0de3bb49b45 pluto[2081]: deleting connection «l2tp-psk»[1] 1.2.3.4 instance with peer 1.2.3.4

The text was updated successfully, but these errors were encountered:

L2tp connection attempt failed because the security layer encountered windows 10

Вопрос

the l2tp connection attemt failed because the security layer encountered a processing error during initial negotiations with the remote computer

we have done settings below

Все ответы

There are two most likely reasons for your problem:

1. Disabled Protocols: In some cases, the error is triggered if the Microsoft CHAP v2 protocol is disabled inside the VPN Connection’s properties. This protocol needs to be enabled in order for most VPN connections to work.

2. PPP Settings: The Point to Point protocol needs to be properly configured before users can attempt a VPN connection. This protocol contains an LCP protocol and the LCP Protocol has some further extensions that need to be enabled in order for the connection to work properly.

To solve your problem, please try the following steps：

1. Make sure that the VPN connection has been properly configured to match the credentials of the VPN server that you are trying to connect to and add the connection.

2. Press “ Windows ” + “ R ” to open the “ Run ” prompt and t ype in “ ncpa.cpl ” and press “Enter” to open the Network Adapter Settings.

3. Right-click on the “ VPN ” connection that has been added and select “ Properties “.

4. Click on the “Security” tab and check the “Allow These Protocols ” option.

5. Check the “Microsoft-CHAP Version 2 ” option and click on “OK”.

6. Click on the “ Options ” tab and select “ PPP Settings “.

7. Check the “Enable LCP Extensions” option and click on the “ OK ” button.

For more details, you can refer the following link:

Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

Hope this can help you, if you have anything unclear, please let me know.

L2tp connection attempt failed because the security layer encountered windows 10

This forum has migrated to Microsoft Q&A. Visit Microsoft Q&A to post new questions.

Asked by:

Question

the l2tp connection attemt failed because the security layer encountered a processing error during initial negotiations with the remote computer

we have done settings below

All replies

There are two most likely reasons for your problem:

1. Disabled Protocols: In some cases, the error is triggered if the Microsoft CHAP v2 protocol is disabled inside the VPN Connection’s properties. This protocol needs to be enabled in order for most VPN connections to work.

2. PPP Settings: The Point to Point protocol needs to be properly configured before users can attempt a VPN connection. This protocol contains an LCP protocol and the LCP Protocol has some further extensions that need to be enabled in order for the connection to work properly.

To solve your problem, please try the following steps：

1. Make sure that the VPN connection has been properly configured to match the credentials of the VPN server that you are trying to connect to and add the connection.

2. Press “ Windows ” + “ R ” to open the “ Run ” prompt and t ype in “ ncpa.cpl ” and press “Enter” to open the Network Adapter Settings.

3. Right-click on the “ VPN ” connection that has been added and select “ Properties “.

4. Click on the “Security” tab and check the “Allow These Protocols ” option.

5. Check the “Microsoft-CHAP Version 2 ” option and click on “OK”.

6. Click on the “ Options ” tab and select “ PPP Settings “.

7. Check the “Enable LCP Extensions” option and click on the “ OK ” button.

For more details, you can refer the following link:

Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

Hope this can help you, if you have anything unclear, please let me know.

The L2TP Connection Attempt Failed Error-It’s Easy to Fix [Partition Magic]

By Ariel | Follow | Last Updated September 12, 2019

Summary :

Recently, a great many users are looking for answers online about the l2tp connection attempt failed error. If you are trying to figure it out, come to this post. MiniTool Solution has explored several effective methods to troubleshoot this problem.

Quick Navigation :

About the L2TP Connection Attempt Failed Error

The l2tp connection is widely used to encrypt and protect Virtual Private Network (VPN) with the layer 2 Tunneling Protocol. VPN can be used to veil the original connection, which helps people to hide their locations from certain websites so as to bypass some security restrictions.

However, many users reported that they fail to make a VPN connection and receive an error message “The l2tp connection attempt failed because the security layer encountered a pressing error during the initial negotiations with the remote computer”.

Possible Causes for “The L2TP Connection Attempt Failed” Error

According to the reports from multiple users we gathered and investigated, there are several possible causes that may trigger the l2tp connection attempt failed error.

• Disabled Protocols: In most scenarios, the l2tp connection attempt failed because the Microsoft CHAP v2 protocol is disabled inside the properties of the VPN connection. Most VPN connections need to enable the protocol to work.
• Improper PPP Settings (Point to Point Protocol): If PPP settings are configured improperly, the VPN connection will be affected. In order to make the VPN connection work smoothly, the protocol that contains an LCP protocol bears some expansions that need to be enabled in order.

Right now, you may have an overall understanding of “the l2tp connection attempt failed” error. Let’s move on to the next following part.

A great many Server users reported that encounter Server execution failed error inside the Add roles and Features wizard.

How to Fix the L2TP Connection Attempt Failed Error

Here are 2 troubleshooting methods with detailed steps.

Method 1. Enable the Microsoft CHAP v2 Protocol

Disabled Microsoft CHAP v2 protocol will trigger the l2tp connection attempt failed problem. So, follow the steps below to enable the protocol.

Please ensure that the VPN connection is configured properly so as to match the credentials of the VPN server when attempting to connect to and add the connection.

Step 1. Press Win + R keys to call out the Run dialog box. Then type “ncpa.cpl” in the box and hit Enter to open up the Network Adapter Settings.

Step 2. Right-click on the VPN connection and select the Properties.

Step 3. Inside the VPN properties, click on the Security tab and check Allow These Protocols option.

Step 4. Check the Microsoft-CHAP Version 2 option and click on OK.

Then you can reconnect the VPN connection and check if the l2tp connection attempt failed error is resolved or not.

Method 2. Enable the LCP Protocol Extensions

As the cause we analyzed above, proper PPP settings are also important to allow LCP extensions. So, let’s see how to enable the LCP extensions in the VPN’s properties.

The first 2 steps are as same as what we have presented in the above method. After opening up the properties of VPN connection, follow the steps below.

Step 1. Inside the properties window, click on the Options tab and select the PPP settings. Then check the Enable LCP Extensions option and click on the OK button.

Step 2.Then click OK to execute the change. After that, you can try to reconnect the VPN connection and see if the problem is fixed or not.

ABOUT THE AUTHOR

Position: Columnist

Ariel is an enthusiastic IT columnist focusing on partition management, data recovery, and Windows issues. She has helped users troubleshot various problems like PS4 corrupted disk, unexpected store exception error, the green screen of death error, etc. If you are searching for methods to optimize your storage device and restore lost data from different storage devices, then Ariel can provide reliable solutions for these issues.