How to Troubleshoot MTU Errors

What is MTU?

The MTU is the Maximum Transmission Unit used by the TCP protocol. TCP stands for Transmission Control Prototcol. The MTU determines the size of packets used by TCP for each transmission of data. Too large of an MTU size may mean retransmissions if the packet encounters a router along its route that can't handle that large a packet.

Too small of an MTU size means relatively more overhead and more acknowledgements that have to be sent and handled. Most cable and some DSL ISPs allow a standard 1500 octet MTU. In general, a 1500 MTU is what you would like to have since it works harmoniously with ethernet, but not all ISPs support an MTU of 1500.

Quoted from Dslreports.com

MTU Error: Xbox Live Working Before

If you're able to connect to Xbox Live before and just encountered this problem, then it might just be temporary. A previously working setup that's suddenly getting a MTU error could mean that the Xbox Live service is actually down or there's something preventing your console's connection to the live service (like latency and packet loss, usually on the ISP's side). You could also consider factors like hardware and software changes like router firmware updates, change of routers, changing of ISPs, etc.

Restart your Network

1. To perform a power cycle, turn off your console, router and modem.
2. Wait for 30 seconds then turn the modem on.
3. Wait for another minute or so until the modem connects to the internet
4. Turn your router on and wait until it boots up completely. This should take another minute.
5. Turn your console on and try connecting again.

Wireless: Improve your signal

Are you connecting to your home network via wireless connection? If your Xbox can only detect one or two bars, you may want to try these steps to improve your wireless signal.

MTU Error: First time set ups

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Personal Firewall

Are you connecting your Xbox 360 to the internet through the PC? Do you have a personal firewall installed? Then it may be blocking some of the outgoing traffic from your console to the Live servers. Please ensure the ports listed in this page are properly enabled. To know more how to enable ports in your ports, please refer to your firewall application’s developer support site.

Router Firewall

Are you connecting your Xbox through a router? Please ensure the ports listed in this page are properly enabled. To know more how to enable ports in your ports, please refer to your router’s manufacturer support page or documentation.

MTU Setting

Are you connecting your Xbox through a router? You may want to configure your router’s MTU setting. The minimum MTU setting for Xbox Live is 1364 while the maximum is 1492. Please consult your router’s documentation to learn how to access this setting.


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