Changing MTU on Windows and Linux

4 min readUpdated December 6, 2025

Let’s look at the methods for changing the MTU value on servers running Windows and Linux.

#Windows

We will make the change using the CMD utility.

First, you need to open Command Prompt as Administrator. Then use the following command to view all existing network interfaces and their MTU values.

bash

netsh interface ipv4 show subinterfaces

Viewing network interfaces and MTU values in Windows

You will get an output similar to this.

Where 1500 (default) is the MTU value.
Ethernet is the default interface name.

Next, change the MTU value with the following command:

bash

netsh interface ipv4 set subinterface "Ethernet" mtu=1400 store=persistent

Where Ethernet is the name of the network interface.
1400 is the new MTU value to be set.

Here is the result.

#Debian / Ubuntu

Run the following command to edit the network interfaces configuration; we will use Nano:

bash

nano /etc/network/interfaces

Then, at the end of the corresponding network interface configuration, add

Adding the mtu 1400 parameter to the network interfaces configuration

Press Ctrl + X, then Y to save the changes.

Run the following command to restart the networking service:

bash

systemctl restart networking

Restarting the networking service after changing MTU

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