Changing Windows MTU: Difference between revisions

Back up to the MTU Page
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<indicator name="Front">[[File:Menu-packet.svg|link=:Category:MTU|30px|Back up to the MTU Page]]</indicator>
<indicator name="Front">[[File:Menu-packet.svg|link=:Category:MTU|30px|Back up to the MTU Page]]</indicator>
[[Category:MTU]]


The MTU (Maximum Transmission Unit) is the size of the largest network packet that can be transferred in a single network transmission without any fragmentation happening.
⚫
Sometimes you may have a reason to change the MTU on your windows computer. Here is how.


We have a separate page on testing your [[MTU]].
⚫
We will show you how to show the existing MTU, and then how to change it, and then how to revert it back to what it was originally.


⚫
Sometimes you may have a reason to change the MTU on your windows computer. Here is how.
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===1. Open Command Prompt as Administrator===

⚫
We will show you how to show the existing MTU, and then how to change it, and then how to revert it back to what it was originally. We're using Windows 10 in this example.

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===1. Open Command Prompt, as Administrator===
# Click <SyntaxHighlight inline>start</SyntaxHighlight>
# Click <SyntaxHighlight inline>start</SyntaxHighlight>
# Type <SyntaxHighlight inline>cmd</SyntaxHighlight>
# Type <SyntaxHighlight inline>cmd</SyntaxHighlight>
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===2. Show the current MTU and the interface name ===
===2. Show the current MTU and the interface name ===
#Enter in the command: <SyntaxHighlight inline>netsh interface ipv4 show subinterfaces </SyntaxHighlight>
#Enter in the command: <SyntaxHighlight inline>netsh interface ipv4 show subinterfaces </SyntaxHighlight>
#Make a note of the existing MTU (probably 1500)
#Make a note of the existing MTU (probably <SyntaxHighlight inline>1500</SyntaxHighlight>)
#Make a note of the interface name - eg Ethernet
#Make a note of the interface name - eg <SyntaxHighlight inline>Ethernet</SyntaxHighlight>


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#Enter the command: <SyntaxHighlight inline>netsh</SyntaxHighlight>
#Enter the command: <SyntaxHighlight inline>netsh</SyntaxHighlight>
#Then: <SyntaxHighlight inline>interface</SyntaxHighlight>
#Then: <SyntaxHighlight inline>interface</SyntaxHighlight>
Then: <SyntaxHighlight inline>ipv4</SyntaxHighlight>
#Then: <SyntaxHighlight inline>ipv4</SyntaxHighlight>
Then: <SyntaxHighlight inline>set subinterface "Ethernet" mtu=1320</SyntaxHighlight>
#Then: <SyntaxHighlight inline>set subinterface "Ethernet" mtu=1320</SyntaxHighlight>
Then: <SyntaxHighlight inline>exit</SyntaxHighlight>
#Then: <SyntaxHighlight inline>exit</SyntaxHighlight>

The screenshot shows all these commands being run...


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<gallery widths=700 heights=400>
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===6. Reverting back===
===6. Reverting back===
# restarting the computer should change the MTU back to default
# Restarting the computer should change the MTU back to default
# Or, you can run the commands above, but set <SyntaxHighlight inline>1500</SyntaxHighlight> instead of <SyntaxHighlight inline>1320</SyntaxHighlight>
# Or, you can run the commands above, but set <SyntaxHighlight inline>1500</SyntaxHighlight> instead of <SyntaxHighlight inline>1320</SyntaxHighlight>

===7. Keeping the MTU change permanent===
If you want to keep thje lower MTU even after a reboot, then re-run the commands, but when you come to change the MTU add <SyntaxHighlight inline>store=persistent</SyntaxHighlight> to the command.

eg <SyntaxHighlight inline>set subinterface "Ethernet" mtu=1320 store=persistent</SyntaxHighlight>

Latest revision as of 12:26, 16 Haziran 2023


The MTU (Maximum Transmission Unit) is the size of the largest network packet that can be transferred in a single network transmission without any fragmentation happening.

We have a separate page on testing your MTU.

Sometimes you may have a reason to change the MTU on your windows computer. Here is how.

We will show you how to show the existing MTU, and then how to change it, and then how to revert it back to what it was originally. We're using Windows 10 in this example.

1. Open Command Prompt, as Administrator

  1. Click start
  2. Type cmd
  3. On the Right hand side, click 'Run as administrator'
  • Open command prompt, as Administrator

    Open command prompt, as Administrator

2. Show the current MTU and the interface name

  1. Enter in the command: netsh interface ipv4 show subinterfaces
  2. Make a note of the existing MTU (probably 1500)
  3. Make a note of the interface name - eg Ethernet
  • Show the current MTU and interface name

    Show the current MTU and interface name

3. Change the MTU for the interface

  1. Enter the command: netsh
  2. Then: interface
  3. Then: ipv4
  4. Then: set subinterface "Ethernet" mtu=1320
  5. Then: exit

The screenshot shows all these commands being run...

  • Changing the MTU to 1320

    Changing the MTU to 1320

5. Check the MTU

  1. Run the first command to show the Interface details again: netsh interface ipv4 show subinterfaces
  2. It should now show 1320

6. Reverting back

  1. Restarting the computer should change the MTU back to default
  2. Or, you can run the commands above, but set 1500 instead of 1320

7. Keeping the MTU change permanent

If you want to keep thje lower MTU even after a reboot, then re-run the commands, but when you come to change the MTU add store=persistent to the command.

eg set subinterface "Ethernet" mtu=1320 store=persistent

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