I cannot connect to an OpenVPN server from a Windows client with the following error in the openvpn.log:
TCP/UDP: Socket bind failed on local address [AF_INET]127.0.0.1:22194: Cannot assign requested address
Exiting due to fatal error
To solve this problem, I have to reboot the computer or restart the Service Host: Network Service, which is very inconvenient.
If the problem occurs when you try to connect to multiple OpenVPN servers at the same time, check that multiple TAP/WinTun virtual network adapters are available in Windows.
In this case, an error will appear in openvpn.log and/or OpenVPN GUI:
All TAP-Windows/WinTun adapters on this system are currently in use
If you have more than one network adapter in Windows, check to see which process/program is using the outbound port that is specified in the details of the error. You can use netstat or PowerShell to find and kill a process that is listening on a specific port:
- TCP port:
Get-Process -Id (Get-NetTCPConnection -LocalPort 22194).OwningProcess
- UDP port:
Get-Process -Id (Get-NetUDPEndpoint -LocalPort 22194).OwningProcess
If no one is listening on the specified port, the computer might have Hyper-V services installed or WSL2 running.
This is because Windows reserves a certain dynamic range of TCP ports for Hyper-V/WSL. You can display this port range with the command:
netsh int ipv4 show excludedportrange tcp
Protocol tcp Port Exclusion Ranges
Start Port End Port
You will get an error if this range overlaps with the outgoing port range of the OpenVPN client:
TCP/UDP: Socket bind failed on local address. Change the outgoing port range in the OpenVPN client settings:
- Right-click on the OpenVPN GUI tray icon;
- Select Settings -> Advanced -> Management interface, and change the Port Offset value so that it is not in the reserved range;
- Save the changes.
After that, you will be able to connect to your OpenVPN server.