Xbox: The Diagnostic Server shows Network Address Translation (NAT) type problems when using Xbox Live (840420)

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With the release of the most recent Dashboard, Xbox Live users can analyze router problems on a more detailed level than they could in previous releases. Through the Dashboard's Connect Status screen (Network Troubleshooter), you can access a new tool called Diagnostic Server. The Diagnostic Server performs various tests to determine whether your router:

• It has an MTU setting that is incompatible with Xbox Live.
• It handles ICMP port-unreachable packets incorrectly.
• It is a highly aggressive NAT-type router.

NAT-type symptoms

With most NAT-type routers, you can connect to the Xbox Live service. However, if you, or other gamers you play, use an aggressive NAT-type router, you may experience some of the following symptoms:

• You can play with one person on your friends list but not another.
• You cannot connect with a particular host in game sessions.
• You cannot hear voice during game sessions, even when you can play without interruption.

What is NAT?

NAT stands for "Network Address Translation." Typically, home users obtain one IP address from their service provider, and then connect multiple devices to their home network. To share one IP address among many devices, a NAT-type router provides a popular solution. NAT makes it possible for each device to use the same IP address and connect to the Internet.

NAT type classifications

Different routers have different methods for performing NAT. Therefore, they are classified by their NAT type as Open, Moderate, or Strict.

How to determine if your router's NAT type is causing problems

To determine if your router's NAT type is causing any one of the symptoms described in the "NAT-type symptoms" section, you must know both your own NAT type and the NAT type of the gamer you are playing. To determine your own NAT type:

1. Select the Y button on the Connect Status screen, and then press the A button to continue to the diagnostic read-outs.
2. You receive the following information in the Diagnostic Server window:
   <Version #>
   NT: x
   NAT Type x=0 ? The API couldn't be called (Couldn't connect to determine NAT)
   x=1 ? Nat with Minimal port assignment, no port filtering (Open)
   x=2 ? Nat with Minimal port assignment, port filtering (Moderate)
   x=3 ? Nat with Aggressive port assignment (Strict)
   
   Note If you use Internet Connection Sharing (ICS) with Windows 2000 Server or with Windows 2000 Pro, you receive a NAT type of 3.

Compatibility table (by NAT type classification)

Use the following table, to determine if the NAT type classification for your router is an issue for you or the gamers you want to play.

	TO OPEN	TO MODERATE	TO STRICT
FROM OPEN	YES	YES	YES
FROM MODERATE	YES	YES	NO
FROM STRICT	YES	NO	NO

For example, you might want to host the latest Xbox Live title, and you verify that your router's NAT type is "Open." Using the table, you can know that your router's NAT type will not prevent your friends (who may also be using a router) from finding your session, hearing your voice, and enjoying a great gaming experience.