Your network does not have a sufficient MTU setting.

If you’re encountering an MTU error when you run an Xbox Live connection test, then you’ve come to the right place! Here are a few quick things to try to get you back on Live!

Restart your network equipment

Power cycle your console and network hardware

Turn off your Xbox 360 console, and then unplug your modem and router. Wait 5 minutes before moving on to the next step.

Plug the modem back in, and be sure to give it at least a full minute to come back online. When it’s up to speed, do the same with your router, and repeat this step for any additional piece of network hardware you‘re using. When all of your network hardware
is running, turn on your console.

Run an Xbox Live connection test

Go to the ‘Settings’ hub on the dashboard (the dashboard is the main menu in your console), select the ‘System’ tile in the upper left, and then ‘Network Settings'. Select the appropriate network (wired or wireless), and then select ‘Test Xbox Live Connection'.

If you still receive an MTU error, try the next step.

Improve your wireless connection

If you’re on a wireless connection, there are a few things to consider for improving your connection. If you’re not on a wireless connection, you can skip ahead to the next section.

Bring the console and your wireless device closer together

Some things to think about when you’re placing your router are the position of the device and its position relative to the console. Make sure your router isn’t on the floor, near any large metal objects (such as kitchen items or a bathroom), or any other wireless
devices, namely 2.4 gigahertz band devices.

You can also try moving the router closer to the console, and make sure that there are no obstructions between the router and the console, if possible. If you are unable to move the router, we suggest moving the console closer to the router/gateway, like
up to the same floor or in the same room.

Change/boost your signal

You can try changing the channel on which your router or gateway broadcasts, as well as switch signal bands if you’re on a dual-band router (for instructions on how to do so on your particular router, be sure to check out our Networking Hardware Information
forums, the hardware manual for your device, or check the manufacturer’s website).

If that doesn't work for you, try out the steps below to simplify your connection.

Simplify your setup

Remove other connections

Unplug everything from your router besides the cables going from your router and modem (or if you’re on a wireless network, turn off all other wireless devices). Your Xbox 360 should be the only thing connected to the router. Make sure the cable running from
your wall jack to your modem is not interrupted by a splitter or other connector.

Run a Live connection test

Go to the ‘Settings’ hub on the dashboard, select the ‘System’ tile and then ‘Network Settings’. Select the appropriate network (wired or wireless), and then select ‘Test Xbox Live Connection'.

If you don’t receive an MTU error after simplifying your setup, it suggests your hardware is having issues managing multiple connections. These next steps should resolve that issue.

Change your router settings

Log into your router settings

We’re almost there! Start your web browser, and in the address bar, type the default IP address for your router or gateway, and press ENTER (be sure to check our Networking Hardware Information forums, the device's hardware manual, or the manufacturer’s website
for this info). IP addresses for popular router and gateway manufacturers are listed below:

Belkin: 192.168.2.1

Linksys: 192.168.1.1

D-Link: 192.168.0.1

NETGEAR: 192.168.0.1 or 192.168.1.1

Enter the user name and password for your router, and then press okay. You can find this in the resources listed above if you do not know the user name and password.

Change your MTU setting to at least 1400

If you’re unsure how to check or change your MTU setting within your router settings, you can check the resources above for them. If you change the MTU setting, be sure to run another Live connection test. If you still encounter an MTU error, move on to the
next step.

Open network ports

For the best results with Xbox Live, you’ll want to ensure the following ports are open:

Port 88 (UDP)

Port 3074 (UDP & TCP)

Port 53 (UDP & TCP)

Port 80 (TCP)

For detailed instructions on how to open your network ports, be sure to check out Manual Port Forwarding in this sticky. If you still encounter an MTU error after forwarding your ports, please move on to the next step.

Determine if your router or gateway need replacing

Okay, you’ve tried all the steps, and you’re still getting MTU errors. At this point we’ll want to check that your router or gateway is compatible with Xbox Live.

Try a direct modem connection

For right now, use an ethernet cord to hook your Xbox 360 console to your modem, bypassing the router entirely. Run a Live connection test, as described earlier in this guide. If you no longer encounter the MTU issue, it indicates your router is not compatible.

Check for hardware compatibility

If a direct modem connection resolves the MTU error, then you’ll want to consider purchasing a new router or gateway. Our Networking Hardware Information forums have an extensive list of supported hardware.

I’m still getting an MTU error. What do I do now?

You may want to give your Internet Service provider a call, to see if they have a resolution for the error on their end. Also, feel free to make a post in the forums, though please be sure to check the questions at the bottom of this post, to better help
us help you!

:)

 

mtu error

MTU Error: Your network does not have a sufficient MTU setting

Go here for solution

http://support.xbox.com/en-US/xbox-...k-does-not-have-sufficient-mtu-setting-979104

 

Problema MTU nella connessione a Internet

Pardon me! This is the support article you'll want to look at: "Your network does not have a sufficient MTU setting."