Detailed Guide: How to Connect to L2TP/IPsec VPN on Windows 10/11

Introduction

VPN (Virtual Private Network) is a technology that allows users to create secure connections to other networks over the internet. L2TP (Layer 2 Tunneling Protocol) combined with IPsec (Internet Protocol Security) creates one of the most secure and popular VPN methods available today.

This article will guide you through the detailed process of setting up and connecting to an L2TP/IPsec VPN on Windows 10 or Windows 11, from initial setup to troubleshooting common issues.

Benefits of L2TP/IPsec VPN

L2TP/IPsec is a combination of two protocols:

• L2TP (Layer 2 Tunneling Protocol): Creates a tunnel for data to travel through
• IPsec (Internet Protocol Security): Provides encryption and security layer

Key benefits include:

• High Security: IPsec provides strong encryption and two-way authentication
• Built-in Integration: Supported on most operating systems with no additional software needed
• Difficult to Block: More difficult for attackers to intercept or monitor
• Good Performance: Good balance between security and speed
• Wide Compatibility: Works with many different network environments

Requirements Before Starting

Before setting up an L2TP/IPsec VPN connection, you'll need:

1. VPN Server Information:

   • IP address or domain name of the VPN server
   • Pre-shared key
   • Login credentials (username and password)

2. Firewall Check:

   • Ensure your firewall allows L2TP/IPsec connections (UDP ports 500 and 4500, IP protocol 50)

3. Updated Windows: Make sure your Windows system is updated to the latest version

Guide to Setting Up L2TP/IPsec VPN Connection

✅ Step 1: Open VPN Settings

1. Press Windows + I to open Settings.
2. Go to Network & Internet > VPN.
3. Click on Add a VPN connection.

✅ Step 2: Add VPN Connection

In the Add a VPN connection dialog:

• VPN provider: Windows (built-in)
• Connection name: Choose a name (e.g., My VPN)
• Server name or address: Enter the IP address or domain name of the VPN server
• VPN type: Select L2TP/IPsec with pre-shared key
• Pre-shared key: Enter the key (you'll get this from your VPN provider/administrator)
• Type of sign-in info: Select one:
  • Username and password (most common)
  • Or use smart card or certificate if required
• Username and Password: (Optional) Enter if you want to save login info

Then click Save.

✅ Step 3: Change VPN Properties (Essential for L2TP/IPsec)

1. Return to the VPN list.
2. Click on your created VPN > Click Advanced options > Click Edit.
3. Scroll down and click More VPN settings (or go to Control Panel > Network and Sharing Center > Change adapter settings).
4. Right-click on the VPN connection > Properties.
5. Go to the Security tab:
   • Type of VPN: Ensure it's Layer 2 Tunneling Protocol with IPsec (L2TP/IPSec)
   • Click Advanced settings > Select Use preshared key for authentication > Enter the key.
6. Go to the Networking tab:
   • Uncheck IPv6 (optional, can be helpful)
   • Ensure Internet Protocol Version 4 (TCP/IPv4) is checked

Click OK.

✅ Step 4: Connect

1. Return to Settings > Network & Internet > VPN.
2. Click on your VPN connection > Connect.
3. Enter your username and password (if not saved), then connect.

Step 5: Verify the Connection

After successfully connecting, you can verify your VPN connection by:

1. Open a web browser and visit a website: https://www.ducxinh.com/tools/my-ip-address
2. Check your IP address. If the VPN connection is successful, the IP address will be that of the VPN server, not your actual IP address.

Troubleshooting Common L2TP/IPsec Connection Issues

💡 Allowing VPN passthrough on router/firewall

If your VPN won't connect, ensure your router or firewall allows:

• UDP ports 500 and 4500
• IP protocol 50 (ESP)

💡 Common errors and solutions

Error 809: "The network connection between your computer and the VPN server could not be established"

• Cause: Typically due to being blocked by firewall or router.
• Solution:
  1. Enable PPTP Pass-Through and L2TP Pass-Through in router settings
  2. Check if NAT-T (NAT Traversal) is enabled

Error 789: "The L2TP connection attempt failed because the security layer encountered a processing error"

• Cause: Issue with security settings.
• Solution:
  1. Double-check the pre-shared key
  2. Try editing the registry (for advanced users):

     HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Rasman\Parameters
     

     Create a new DWORD value: AllowL2TPWeakCrypto and set it to 1

Error 800: "The remote connection was not made because the attempted VPN tunnels failed"

• Cause: Server not responding or incorrectly configured.
• Solution:
  1. Verify the server address
  2. Check your internet connection and firewall

Advanced Settings

Automatically Connect VPN at Startup

To automatically connect to your VPN when Windows starts:

1. Open Command Prompt with Administrator privileges
2. Enter the following command (replace "My VPN" with your VPN connection name):

powershell -command "Add-VpnConnection -Name 'My VPN' -SplitTunneling $False -PassThru | Set-VpnConnection -AutoTrigger 2"

Create a Quick Connection Shortcut

1. Right-click on the Desktop > New > Shortcut
2. In the "Type the location of the item" field, enter:

   rasphone -d "My VPN"
   

   (Replace "My VPN" with your VPN connection name)
3. Name it and finish creating the shortcut

Comparison of Popular VPN Protocols

Conclusion

Setting up an L2TP/IPsec VPN connection on Windows 10/11 is an effective way to protect your internet connection and securely access private networks remotely. While there are many other VPN protocols available, L2TP/IPsec remains a popular choice due to the balance of security, performance, and built-in integration with the operating system.

If you experience difficulties during setup, follow the troubleshooting steps mentioned above or consult with your network administrator.

Note: Always ensure that you're only connecting to trusted VPN services and are permitted to use them according to your organization's policies.