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How to Change MTU Size on Windows 11

How to Change MTU Size on Windows 11

In this article, we’ll see how to change MTU size on Windows 11. Maximum Transmission Unit, or MTU, is the maximum number of bytes that can be transmitted over the network. The default MTU size in Windows is 1500 bytes. However, it can vary depending on your network type.

It’s important to have an optimal MTU size as it influences the speed and reliability of data transmission. Your internet will slow down if the MTU size is too small. If you increase the MTU size to a level more than your network adapter can support, then you will experience packet loss, ultimately causing network issues.

Therefore, setting the MTU size to the correct value is important to enjoy an interrupted fast connection. Read along to know how to find the MTU size on Windows 11. We’ll also check out how to change MTU size on Windows 11.

How to Check MTU Size on Windows 11

Command to Check the MTU Size in Command Prompt

Before making any changes, it’s important to check your current time MTU size. To do that, open the Start Menu, type Command Prompt in the search bar, and press Enter. In the Command Prompt window, type netsh interface ipv4 show subinterfaces and press Enter.

You’ll see the current MTU size under the MTU column.

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How to Find the Best MTU Size

The quickest way to find the best MTU size for your network is by doing a ping test. In this test, you’ll send multiple ping requests while slowly decreasing the package size until it no longer requires fragmentation.

Here’s how to do the ping test on Windows 11:

  1. Open Command Prompt, type the following command, and press Enter. Make sure to replace the Domain_Name with a pingable domain.
    Ping Domain_Name -f -l 1500

    Ping command to Change MTU Size on Windows 11

  2. If you get the message ‘Packet needs to be fragmented but DF set,’ reduce the packet size by 10 and perform the test again.
    Packet needs to be fragmented but DF set command in between to Change MTU Size on Windows 11
  3. You must keep reducing the packet size until the ‘Packet needs to be fragmented but DF set’ message no longer appears.
    No fragmentation required message in Command Prompt

After you find the maximum packet size that doesn’t require fragmentation, add 28 to it. Here, 20 bytes are reserved for the IP header, and the remaining 8 are required for the ICMP echo request header.

For instance, if you find that 1460 is the maximum packet size that doesn’t require fragmentation, add 28 to it. So, the optimal MTU size for your network adapter is 1488.

Now, let’s check out how to change MTU size on Windows 11.

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How to Change MTU Size on Windows 11

Having known the optimal MTU size, here’s how to change it.

  1. In the Start Menu, type Command Prompt and choose Run as administrator from the right pane.
  2. Type netsh interface ipv4 show subinterfaces and press Enter. Note down your Interface name. For us, it’s Wi-Fi.
    Command to Check the MTU Size in Command Prompt
  3. Type the following command and press Enter. Make sure to replace Wi-Fi with your Interface name. Also, replace the mtu size value with the one you find the best for your computer in the ping test.
    netsh int ipv4 set subinterface “Wi-Fi” mtu=1488 store=persistent

    MTU changing command to Change MTU Size on Windows 11

And that’s about it. Restart your computer, and you have successfully changed the MTU size on Windows 11.

What is the default MTU size in Windows?

The default MTU size in Windows 11 is 1500 bytes. To confirm this, open Command Prompt, type netsh interface ipv4 show subinterfaces, and press Enter. You’ll see the MTU size in the MTU column.

How do I change the MTU size in Windows 11?

Before you change MTU size on Windows 11, you must know the optimal MTU size that is best for your system. You can check that by doing a ping test. Once you have the optimal number, change the MTU size using your router setting or Command Prompt.

Read Next: How to Backup and Restore GPU Preference Settings for Apps in Windows 11

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