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The L2TP Connection Attempt Failed Because The Security Layer Encountered A Processing Error, Get The Solutions And Fixes

The L2TP connection attempt failed is something that you might experience while using a VPN service. The LT2P encryption is widely used, so it is easy to find solutions for problems related to it. Read this article to get all the info on the L2TP connection attempt failed because the security layer encountered a processing error.

by Vishwesh Rajan P | Updated Jan 12, 2022 15:31 PM

The L2TP Connection Attempt Failed Because The Security Layer Encountered A Processing Error, Get The Solutions And Fixes
Source: Twitter

What is L2TP Connection?

Layer 2 Tunneling Protocol is a tunneling protocol used in computer networking to facilitate virtual private networks or as part of ISP service delivery. It merely encrypts its own control messages and does not provide any encryption or content confidentiality on its own. Rather, it creates a tunnel for Layer 2 traffic (which can be encrypted), which can then be transmitted through a Layer 3 encryption protocol like IPsec.There are several reasons why a connection attempt might fail in this protocol. Scroll down to learn more about it!

How to Fix L2TP Connection Attempt Failed because the Security Layers Encountered a Processing Error?

Listed below are some of the ways to fix the problem,

Turn on Microsoft CHAP v2 Protocol

  • To open the Run command window, right-click on the Start menu and select Run.

  • To open the Network Connections window, type ncpa.cpl in the Run command search box and press Enter.

  • Right-click on your VPN connection in the Network Connections window and select Properties.

  • Go to the Security tab in the VPN Properties dialogue box and choose the radio button next to Allow these protocols.

Make sure that the box next to Microsoft CHAP Version 2 (MS-Chap v2) is checked.

Press OK to save changes and exit. Trying to run the connection again and see if the solution is fixed.

Turn on LCP Protocol Extensions

  • To launch the Run command box, press the Win + R keys on your keyboard together.

  • In the Run command search area, type ncpa.cpl and hit OK.

  • Locate the VPN in the Network Connections window that appears, right-click on it, and select Properties.

  • This time, navigate to the VPN Properties window's Options tab and click the PPP Settings button.

  • Check the box next to Enable LCP extensions in the PPP Settings dialogue box.

Click OK to save changes and exit and check if the issue is resolved.

Restart IPSec Service

  • To open the Run command, press the Win + X shortcut on your keyboard and pick Run.

  • Type services.msc into the Run command window and press Enter.

  • The Service Manager window will open as a result of this. Look for IKE and AuthIP IPSec Keying Modules under the Name column on the right side of the Service Manager.

  • If it appears to be operating, right-click it and choose Restart.

  • Double-click it now, and in the Properties box, go to the Startup type section under the General tab.

  • Change the field's value to Automatic.

  • To save your changes and exit, press Apply and then OK.

  • Repeat the last two steps for the IPSec Policy Agent service.

Restart the VPN connection and check if the issue is resolved.

Reinstall the Network Adapter

  • Select Run from the Start menu by right-clicking on it. This will bring up the Run command prompt.

  • Type devmgmt.msc into the Run command box and press Enter.

  • Navigate to Network adapters and expand the section in the Device Manager window that appears.

  • Locate your VPN's network adapter, right-click it, and select Uninstall device.

  • To confirm the action, click the Uninstall option in the popup that appears. 

Restart your computer once the program has been uninstalled. The gadget is automatically reinstalled and reset to its default settings. You should also double-check that both the client and the server are using the correct certificate. If you're using a PSK (Pre Shared Key), make sure it's the same on both the client and the VPN server.

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The L2TP Connection failed because the security layer encountered a processing error: FAQs

1. What is L2TP Connection?

Layer 2 Tunneling Protocol is a tunneling protocol used in computer networking to facilitate virtual private networks or as part of ISP service delivery.

2. When was this protocol first published?

It was published in the year 2000.

3. What does VPN stand for?

It stands for Virtual Private Network.

4. What does WAN stand for?

It stands for Wide Area Network.

5. How is a VPN created?

A VPN is created by establishing a virtual point-to-point connection through the use of dedicated circuits or with tunneling protocols over existing networks.

6. What are the benefits of using a VPN?

Increased functionality, security, and control of the private network are all advantages of using a VPN.

7. Is Encryption an inherent part of VPN?

It is common but not inherent.