Getting an error when connecting to VPN "The L2TP connection attempt failed .."

Question

Hi,

I am having an error when conencting to VPN, "The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer." It's weird because I was just able to connect last week, all of a sudden it is having this error.

I just installed Windows 11 hoping that it would be solved but did not at all (I had Windows 10). Last update was 07/14/2023, but I was able to connect to the VPN between 07/15/23-07/27/23, then the latest update would be 08/01/2023, so unsure if this is an update issue?

Any help would be appreciated,

Thank you

Answer 1

Finally Fixed my LT2P issue on Windows 11 devices. I had tried everything here and on other blogs but here was my fix.

Open Device Manager and expand network adapters. Uninstall all miniport adapters, then Scan for Hardware Changes. Worked immediately! I’m shocked that did it but I’m glad to get this finally resolved.

Answer 2

Hello AVN,

Thank you for your question and for reaching out with your question today.

The error message "The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer" typically indicates an issue with the L2TP (Layer 2 Tunneling Protocol) VPN connection. This error can occur due to various reasons, including network configuration changes, software updates, or issues with the VPN server.

Here are some troubleshooting steps to help you resolve the L2TP VPN connection issue:

1. **Check VPN Server Status:**
   Ensure that the VPN server you are trying to connect to is up and running. If possible, try connecting from a different device to see if the issue is specific to your Windows 11 machine.

2. **Verify VPN Server Settings:**
   Double-check the VPN server settings, including the authentication method, encryption settings, and shared secret (pre-shared key). Ensure that the settings on the client side match those on the server side.

3. **Restart Router and Modem:**
   Sometimes, network devices like routers and modems can cause temporary connectivity issues. Try restarting your router and modem to see if it resolves the problem.

4. **Check Windows Firewall and Security Software:**
   Make sure that Windows Firewall or any third-party security software is not blocking the VPN connection. Temporarily disable any security software and try connecting again.

5. **Update Network Drivers:**
   Ensure that your network adapter drivers are up to date. Outdated or incompatible network drivers can cause connection issues. Visit the manufacturer's website to download and install the latest drivers for your network adapter.

6. **Check VPN Connection Settings:**
   Verify that the VPN connection settings (including username, password, and server address) are correct. A small typo in the server address or incorrect authentication details can lead to connection failures.

7. **Try a Different VPN Protocol:**
   If your VPN server supports multiple protocols, try connecting using a different VPN protocol (e.g., IKEv2, SSTP) to see if it resolves the issue.

8. **Recreate the VPN Connection:**
   Delete the existing VPN connection on your Windows 11 machine and create a new one with the correct settings.

9. **Check for Recent Windows Updates:**
   While you mentioned you installed Windows 11 and received updates, it's worth checking if there are any newer updates available that might address VPN-related issues.

10. **Contact VPN Provider Support:**
    If you have followed the troubleshooting steps above and still cannot connect to the VPN, consider reaching out to your VPN provider's support team for further assistance. They may have specific recommendations or solutions for their service.

Remember to restart your Windows 11 machine after making changes to the VPN settings or network configuration.

I used AI provided by ChatGPT to formulate part of this response. I have verified that the information is accurate before sharing it with you.

If the reply was helpful, please don’t forget to upvote or accept as answer.

Best regards.

Answer 3

This is the second time I fixed this this problem. Hope it works for you.

I bring my laptop work. Connect it to office wi-fi at work. VPN through office wi-fi. After this, VPN also works at home.

It seems something to do with security.