Instructions
Unplug any wireless adapters or network cables if you want to use the built-in Wi-Fi to connect. Go to the XBox menu and select "My XBox." Select "System Settings" and look at the number of bars your connection provides. Try configuring your settings by selecting "Configure Network." Select "Wireless Mode" under the "Basic Settings" tab. Scan for networks and enter your wireless password. Select "Done" and test your XBox Live by pressing the "B" button. Reset your wireless settings in the "Configure Network" tab. Select "Additional Settings" and then "Restore to Factory Defaults." Confirm by selecting "Yes" and turn off the console after it finishes. Power up your console and try to connect again.
Secure the wireless adapter's USB cord to the console if you want to use a wireless network adapter to connect. Make sure the antennae are flipped up for optimal signal. Unplug the USB connector and plug it back in if the Wireless Networking Adapter's light is not on. Try every other USB port on the console if you are still experiencing issues. Contact support if the adapter's lights are flashing red. Use the same method for the Wireless G Networking Adapter model.
Move objects or interfering signals from the path of the wireless router or gateway that may keep it from working. Move the source of your wireless Internet signal and the console closer together for a better connection. Try turning off other wireless devices to see if the cause of the issue is interfering signals. Test your XBox Live connection in the "Network" tab after making any of these changes.
Add your XBox console's MAC address if your router or gateway is using MAC filtering. Find your console's MAC address by going to "My XBox" on the console's main screen. Select "System Settings" and then "Network Settings." Select "Configure Network" and then "Advanced Settings" on the "Additional Settings" tab.
Try plugging your console in for a wired connection by inserting one end of a network cable into your console and the other end into your router or gateway. Test your XBox Live connection in the "Network" tab.
Change your router or gateway to "Mixed Mode" if you have an N or 802.11n type router. Consult your specific router's guide to complete this task.