Tool: MTU-Optimizer – automatically find the best MTU

Today I would like to present you again a small tool from “own production”. The tool I’m talking about is called MTU-Optimizer. The name already gives an indication of what the tool can do for you: It determines the MTU (Maximum Transmission Unit) and can set it for any network card.

Like most of my tools, the MTU Optimizer is programmed in C# and designed as portable application. (This means: It does not require any installation and can be started, for example, from a USB flash drive.) The download link to the tool can be found at the end of this article. Beforehand, however, I would like to briefly discuss the capabilities of the tool. Therefore we should first have a look at what the MTU is all about.

What is MTU?

MTU is the abbreviation for Maximum Transmission Unit and is the maximum packet size within a protocol. If the data packetsize exceeds the MTU – i.e. there is more data than fits in a frame (= transmission unit), fragmentation occurs. This means that the data must be split into several packets to be transferred, which can lead to a reduction in the transmission speed up to connection breaks. It is therefore important that the MTU isn’t configured too large.

The MTU setting is made in the system settings of the computer (and there usually in the network settings). Anyone who has read carefully will find that a (Wireless-)Lan interface should normally have two MTUs. One for IPv4 and one for IPv6 – after all, the MTU is valid for one protocol.

How may the MTU Optimizer help you?

MTU Optimizer ScreenshotThe MTU Optimizer is a small tool that determines the optimal MTU value (for the IPv4 protocol) of the network interfaces present in your computer. For this purpose, the MTU optimizer tests stepwise from the top down to the maximum possible MTU value. After the MTU Optimizer has determined the ideal MTU, it can be set from the tool to any network interface.

To determine the MTU, simply click on the “Analyze MTU” button (1). The network interface for which the determined MTU shall be set can be selected in the interface list (2). The column MTU (3) indicates which MTU value is currently set for the specific interface. This allows you to check whether the optimal MTU has already been configured. By clicking on the “Set MTU for selected interfaces” button (4), the determined ideal MTU can be set for all selected interfaces. (If the settings do not work, please close the MTU Optimizer and re-open it by right-clicking –> “Run as administrator”.

Current Version & Download

The current version of the MTU Optimizer can be downloaded via the following link. For updates, the MTU Optimizer informs you independently.

MTU Optimizer Logo
Download: MTU Optimizer


With my own connection (Telekom Magenta Hybrid), the MTU optimizer has already proven itself, because the MTU of hybrid connections is slightly lower than with conventional DSL connections (because of the larger protocol overhead). Could you improve your connection with the MTU Optimizer, too? Let me know it! For feedback, questions and ideas, the commentary is always available.


  1. What destination does MTU Optimizer uses? It seems that VPN Analyzing just does not work, because the destination is somewhere in the Internet?
    Also, how do you determin a higher MTU if the the interface is configured do something like 1300 and the MTU of the network got bigger?


    • Hello Herbert,

      thanks for your questions. Yes, the tool tests against external server. As first attempt: and as fallback Higher MTU values are tested, by internally starting with an MTU of 1500 and then getting lower until it package fragmentation stops.

      For a better understanding I uploaded the source code on GitHub:
      So feel free to copy, fork, adjust and/or improve the project.

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