How to Change MTU Size in Windows 11: A Step-by-Step Guide

If you’re experiencing slow internet speeds, lag during online gaming, or connection drops on your Windows 11 PC, tweaking your MTU (Maximum Transmission Unit) size could make a real difference. In this step-by-step guide, we’ll show you how to change the MTU size in Windows 11, explain why it matters, and share best practices for optimizing network performance.

Whether you’re a beginner or an advanced user, this detailed walkthrough covers everything you need to know — from checking your current MTU value to setting a custom one safely.

🧭 Quick Summary: Changing MTU Size in Windows 11

What Is MTU and Why Does It Matter?

MTU (Maximum Transmission Unit) refers to the largest size (in bytes) of a data packet that can be sent over a network connection. It’s a critical setting that affects how efficiently data travels between your computer and the internet.

• The default MTU value in most Windows systems is 1500 bytes.

• However, depending on your ISP, router, VPN, or network configuration, this might not be the optimal size.

Why Changing MTU Size Can Improve Performance

A properly configured MTU can:

• Reduce latency during online gaming.

• Prevent packet fragmentation.

• Increase download and upload speeds.

• Fix issues like connection timeouts or website loading errors.

For example, if your MTU is too high, packets may be fragmented, slowing data transfer. If it’s too low, performance might drop because of unnecessary overhead. Finding the sweet spot ensures smoother and faster communication.

How to Check the Current MTU Size in Windows 11

Before making any changes, it’s smart to check your current MTU value.

Step 1: Open Command Prompt

1. Press Windows + S and type cmd.

2. Right-click Command Prompt → select Run as administrator.

Step 2: Run the Network Command

Type the following command and hit Enter:

Step 3: Note the MTU Value

You’ll see a list of network interfaces like Ethernet, Wi-Fi, or VPN. Look for your active connection (for example, “Wi-Fi” or “Ethernet”) and note its MTU value under the “MTU” column.

Example output:

In this example, the current MTU size is 1500.

How to Find the Optimal MTU Size for Your Connection

Not every connection performs best at 1500 bytes. You can test and determine the maximum MTU value your network supports without fragmentation.

Step 1: Open Command Prompt as Administrator

Same as before — open Command Prompt (Admin).

Step 2: Use the Ping Command

Type:

Here’s what each part means:

• ping — tests network connectivity.

• google.com — the target server.

• -f — prevents packet fragmentation.

• -l — specifies the packet size (in bytes).

Step 3: Adjust the Packet Size

• If you get a message like “Packet needs to be fragmented”, reduce the number (e.g., 1464, 1452, etc.).

• Keep lowering until the message disappears.

When the ping succeeds without fragmentation, add 28 bytes (for IP and ICMP headers) to the number.
👉 That total is your ideal MTU value.

Example:
If the largest successful ping is 1472, your optimal MTU = 1472 + 28 = 1500.

How to Change the MTU Size in Windows 11

Once you know your ideal MTU value, follow these steps to set it.

Method 1: Change MTU Size Using Command Prompt

1. Open Command Prompt as Administrator.

2. Identify your interface name again:

   netsh interface ipv4 show subinterfaces


3. Set the new MTU value:

   netsh interface ipv4 set subinterface "Wi-Fi" mtu=1472 store=persistent


   (Replace “Wi-Fi” with your active connection name and 1472 with your desired MTU value.)

4. Restart your computer for the changes to take effect.

Method 2: Change MTU Using PowerShell

1. Open PowerShell (Admin).

2. Run:

   Get-NetIPInterface


   This displays all network interfaces.

3. Note the InterfaceAlias for your connection.

4. Use the command:

   Set-NetIPInterface -InterfaceAlias "Wi-Fi" -NlMtu 1472


5. Restart your computer.

How to Verify the MTU Change

After rebooting:

1. Open Command Prompt (Admin).

2. Run:

   netsh interface ipv4 show subinterfaces


3. Check if your interface shows the updated MTU value.

If it matches the number you set, congratulations — you’ve successfully changed your MTU size!

When Should You Change the MTU Size?

You should consider adjusting the MTU if you experience any of the following:

• Slow or unstable internet connections.

• Frequent VPN disconnections.

• Streaming issues (videos buffering or lagging).

• Gaming latency or random lag spikes.

• Websites that don’t fully load or time out.

Tweaking MTU can often solve these issues without needing a new router or ISP call.

Common MTU Values for Different Networks

Here’s a quick reference table to help you choose a starting point:

💡 Tip: VPNs often require smaller MTU values due to encryption overhead.

Advanced: Change MTU Size via Registry Editor (For Experienced Users)

If you prefer a manual, persistent change, you can edit the Windows Registry — though this is more advanced.

⚠️ Warning: Incorrect registry edits can harm your system. Back up your registry before proceeding.

Step-by-Step Registry Method

1. Press Windows + R, type regedit, and press Enter.

2. Navigate to:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces


3. You’ll see several long alphanumeric folders — each represents a network adapter.

4. Open each one and find the correct adapter by checking the DhcpIPAddress value.

5. Right-click in the right pane → New > DWORD (32-bit) Value.

6. Name it:

   MTU


7. Double-click it and set:

   • Base: Decimal

   • Value data: Your desired MTU (e.g., 1472)

8. Click OK, then Restart your PC.

Troubleshooting MTU Issues in Windows 11

If your connection becomes unstable or slow after changing MTU, try these steps:

1. Revert to Default:
   Use:

   netsh interface ipv4 set subinterface "Wi-Fi" mtu=1500 store=persistent


2. Update Network Drivers:
   Go to Device Manager → Network adapters → Right-click → Update driver.

3. Reset Network Settings:

   netsh int ip reset


   Then restart your computer.

4. Test With Different Values:
   Some networks perform best with 1472 or 1492 instead of 1500.

Tips for Optimizing Internet Speed After Changing MTU

• Restart your router to ensure all network settings sync properly.

• Disable unused VPNs if they force a smaller MTU.

• Run a speed test before and after changes to compare performance.

• Keep firmware updated on your modem/router.

Understanding MTU Fragmentation

When an MTU is set too high, data packets may exceed the allowed size, forcing fragmentation — breaking them into smaller chunks.

Why It’s Bad

• Increases CPU overhead.

• Slows data transmission.

• Causes packet loss in some cases.

By testing and optimizing MTU, you ensure packets fit perfectly within limits — resulting in smoother communication.

Key Takeaways

• MTU determines the largest data packet size your PC can send.

• Default MTU is 1500, but it’s not always optimal.

• Use ping tests to find the best MTU size.

• Change MTU via Command Prompt, PowerShell, or Registry Editor.

• Verify results using netsh commands after reboot.

• Adjust if you face lag, fragmentation, or speed issues.

Conclusion

Changing the MTU size in Windows 11 is one of the simplest yet most effective ways to troubleshoot and optimize your internet performance. Whether you’re trying to reduce gaming lag, speed up downloads, or fix unstable VPN connections, adjusting this value can help.

Just remember — always test before you tweak. Once you find the right MTU setting, you’ll likely notice a smoother and faster connection almost immediately.

FAQs About Changing MTU Size in Windows 11

1. What is the default MTU size in Windows 11?

The default MTU value is usually 1500 bytes for Ethernet and Wi-Fi connections.

2. What MTU value should I use for VPN connections?

VPNs typically work best with MTU values between 1400 and 1472, depending on the encryption protocol.

3. Will changing MTU improve gaming performance?

Yes, if you experience lag or latency issues, optimizing your MTU can reduce packet loss and improve stability.

4. Is it safe to change MTU settings?

Yes, as long as you test values before applying and note your original MTU to revert if needed.

5. How do I reset MTU to default in Windows 11?

Use this command:

Then restart your computer.

Ready to boost your connection speed? Follow the steps above to find your ideal MTU size and enjoy a faster, smoother Windows 11 experience.