Instructions
Turn on your Xbox 360 console and highlight the "My Xbox" tab.
Press to the right on the left control stick or the directional pad to reach the "System Settings" tab. Press the "A" button.
Press down on the left control stick or directional pad to highlight "Network Settings." Press the "A" button.
Scroll down to "Test Xbox Live Connection" and press the "A" button.
Highlight "Yes" and press the "A" button to sign out from Xbox Live and begin the connection test.