Restart the PC

1. Click the Start button.
2. Click the Power button. Now select Restart.
   
3. Wait for your PC to reboot.

Although this is a basic fix, it is one of the most efficient methods to troubleshoot most PC problems. The locked connection is closed after a reboot and the VPN can create a new connection. So be sure to try this method if you’re getting VPN error The specified port is already open on Windows 11.

Use the Registry Editor

1. Press the Windows key + R, input regedit in the box, and press Enter key.
2. In the Registry Editor, navigate using the following path:
   

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   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

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3. Right-click the right pane, choose New, and select Multi-string Value.
4. Rename it to ReservedPorts and open it.
5. Input 1723-1723 in the Value data box and click OK.
   
6. Close and restart the PC to take effect.

By editing the registry, you might fix VPN The specified port is already open when using L2TP protocol, so be sure to try this method.

Modify connection port in Command prompt

1. Press the Windows key, search for command prompt and select Command Prompt from the list of results.
2. Input the following code:
   

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   netstat -aon 

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3. Identify process PID for any program using port 1723.
4. Input the following command and press Enter key. We used this command as an example, but you’ll need to change the number at the end so it matches your process:
   

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   taskkill /F /PID 1242

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5. Close Command Prompt.
6. Restart PC to take effect.

Use the Control Panel

1. Press the Windows key, search for control panel and launch it.
2. Change the view by to Small icons and select Phone and Modem.
   
3. Open the Modems tab, choose the modem and click Remove.
   
4. Restart PC to take effect.