Openvpn mtu windows

Open your server. This will prevent OpenVPN from tweaking the buffer size between the server and the client. It will be determined by the OS. Windows users who connect to a Linux server will experience faster speeds. If for some reason this is not possible, e. Try these lines:. You might be wondering why and how these tweaks work?

Let's refer to the history of OpenVPN. In the year , OpenVPN had a problem with different buffer sizes on different platforms. To unify the data transfer channel, developers set the fixed buffers to 64Kb. However, this caused completely strange issues with the MTU for all adapters in Windows.

To fix it, developers hardcoded these lines, which work for non-Windows based servers and clients:. These lines are still presented in the OpenVPN source code, so that is why we are getting the slowdown! Try with these lines in your config:. I hope this article was helpful for you. Share your speed results if you saw a significant improvement via habr. Winaero greatly relies on your support.

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Thanks for your support! Sergey Tkachenko is a software developer from Russia who started Winaero back in On this blog, Sergey is writing about everything connected to Microsoft, Windows and popular software.

Follow him on Telegram , Twitter , and YouTube. View all posts by Sergey Tkachenko. My boy Chryscznaag told me about this and I checked it out. The changes did improve the download speed. Finding an apartment in Berlin is hard and I had to switch between many before finding a permanent contract. A few times during this process I found that my VPN stopped working after moving to a new apartment. It took a little bit of investigation but I found the culprit to be the MTU setting.

It turns out that misconfiguration of the MTU can cause problems and even stop requests working so getting it right is important. The process is repeated until the smallest successful packet size is found. See below for how we will do this manually. Here is a table from wikipedia on the subject:. We will start from the Ethernet v2 standard from the table above as this should cover all ISPs, and reduce the packet size by 10 until we get a successful response.

So my MTU was after the last request was successful. This is due to Google sending back a small response. The request was successful though.

This makes it a pleasure to work with because a lot of the functionality feels familiar. Setting up OpenVPN is one of those command-line-only features. However, after downloading the. The CPU! On my first speed test, download speeds were around 15 Mbps download and 12 Mbps upload.

If you are using OpenVPN in a hardware-restricted setup, then give the following config tweaks a try. My ISP download speed is just over Mbps. My plan? Improve OpenVPN performance as much as possible to least hit 20 Mbps download speeds, as you can see from the above before vs. In my case, its servers that are located in South Miami. Not much to elaborate on here… Closer is generally faster.

Still, you should test locations for yourself because not all servers perform equally.