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Troubleshooting OpenVPN - Tips for connecting with the OpenVPN client

This article is directed for users of OpenVPN. It is for troubleshooting client connection issues. It assumes that the OpenVPN server you are connecting to is fully functional and properly configured. This article is for users of the Windows version of the OpenVPN client.


Error: "OpenVPN connects but I cannot reach the internet"

Your log file will show the following error: 'Initialization sequence completed with errors'. You can view the log file by right clicking on the OpenVPN-GUI icon in the system tray and selecting 'view log'.

This error is most commonly due to the Windows (or other) firewall blocking the TAP adapter. If you are using a different firewall than Windows, check your vendor's manual on how to allow programs to pass through. Sometimes there will be a button that lists programs that are allowed. Find OpenVPN and allow access.

If using Windows firewall, go to the 'Control Panel' and select 'Firewall' and then the 'Advanced' tab. Select the connection that corresponds to your TAP adapter. Uncheck the box next to it and select 'OK'. Reboot your computer to ensure the setting takes effect.


Error: "Replay-window backtrack occurred"

Sometimes network congestion and latency cause the UDP protocol, most commonly used with OpenVPN, to drop packets and even lose the connection. You will see a 'Replay window backtrack occurred' error in the log if this is occurring. One solution is to switch to the TCP protocol, assuming your server is configured to support a TCP connection.


Error: "Bandwidth speed seems to be slow or even drop"

1) The OpenVPN default installation in Windows is set to 'Normal Priority'. For the average user, this is probably reasonable. In some cases, on computers that have a lot of other processing going on, the processor might become highly loaded. This shares less processing time to the VPN, slowing things down. This can be fixed by setting the priority of the application to 'High'. This setting is adjusted in the Windows registry. Before performing any registry adjustments it is wise to make a backup just in case.


--Select 'Start' and then 'Run' and then type 'regedit' and hit enter


--Click on 'OpenVPN' and then click 'priority'


--Find 'OpenVPN-GUI' and repeat

--Close regedit and you are set


2) A good deal of performance can be gained by optimizing Windows TCP in Windows XP. Windows Vista is fairly well managed and does not respond as well to any tweaks. The easiest way to accomplish this is by using a TCP optimizing program. We've used one from that works well and eliminates the need to make manual registry settings. It also will back up your settings before making changes so you can always go back to where you started. We've found that these tweaks in Windows XP have resulted in much faster web surfing in many but not all cases.


Error: "TLS Error: TLS key negotiation failed to occur within 60 seconds"

This error will show on your login screen and in the OpenVPN log. The most common cause of this error is no connectivity to the internet. Make sure you can reach the internet without the VPN. In some cases, your network provider may be blocking the UDP protocol or various ports. Depending on how the server you are attached to is configured, you might try alternate ports or the TCP protocol. In most cases, some combination of ports and TCP resolves the blockage.


Error: "I connect but my IP address has not changed or the TAP Driver fails to load."

This is a Windows Vista or WIndows 7issue that is easily resolved. OpenVPN must be installed by right clicking on the program and selecting the 'Run as administrator' option. Otherwise, the TAP driver will not load properly. Once installed, the program has to be launched in the same way or you will connect to the OpenVPN server but Vista will not allow OpenVPN to set the route and the VPN will fail.


Error: "The OpenVPN-GUI icon drops off from the system tray."

This is a Windows issue where the icon does not show but OpenVPN is still running. Hit ctrl-alt-delete which will launch Task Manager. Select the 'process' button and search for 'OpenVPN-GUI'. Kill the process and close Task Manager. Re-launch OpenVPN from your shortcut or the Start Menu.

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