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How to change MTU Value
By On April 18, 2015

How to change MTU Value

MTU – Maximum Transmission Unit of a communications protocol of a layer is the size (in bytes) of the largest protocol data unit that the layer can pass onwards. MTU parameters usually appear in association with a communications interface (NIC, serial port, etc.). Standards (Ethernet, for example) can fix the size of an MTU; or systems (such as point-to-point serial links) may decide MTU at connect time.

A larger MTU brings greater efficiency because each network packet carries more user data while protocol overheads, such as headers or underlying per-packet delays, remain fixed; the resulting higher efficiency means an improvement in bulk protocol throughput. A larger MTU also means processing of fewer packets for the same amount of data. In some systems, per-packet-processing can be a critical performance limitation.

Why do you want/need to change MTU?

Wrong or very high MTU value can cause ERR_CONNECTION_RESET error on Chrome. You will not be able to visit few websites not only from chrome but Firefox and IE as well. Refer to ERR CONNECTION RESET – wrong MTU maybe the culprit

Here are the Steps to Follow

  1. Click Start, and then type cmd in the Start Search box.
  2. In the search results list, right-click Command Prompt, and then click Run as Administrator.
  3. When you are prompted by User Account Control, click Continue.
  4. At the command prompt, type netsh interface ipv4 set subinterface “Local Area Connection” mtu=nnnn store=persistent and then press Enter.
    How to change MTU Value.

    How to change MTU Value.

    Note: “Local Area Connection” (including quotation marks as there is space in the name) is the name of the network connection on the computer, which is shown in the listing of network interfaces available. Common network connection name for Wi-Fi access is “Wireless Network Connection”. Since I have 2 LAN on my PC I have a Local Area Connection 2 as well but no Wireless.
    In addition, nnnn should be replaced with numeric value of the preferred size of MTU, with minimum of 576 for IPv4 and 1280 for IPv6. Note that if a value greater than the dynamically-determined MTU, the system uses the value of the dynamically-determined MTU instead. Thus, change of MTU is normally to reduce and reduce, but not to increase, the size of the MTU.

  5. Type netsh int ip show int and then press Enter to check if the value was changed.

I hope you find this tutorial useful. It is also possible to change MTU value using Registry Editorregedit but I like to keep things simple and this (cmd) is faster and better.


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About The Author
Geek Deepak
CEO & Editor in Chief of Geeks Column