If you have to swap the Ethernet cable between your PC and your Xbox 360 console to access Xbox LIVE, you may have to copy the MAC address of your PC to your Xbox 360 console.
If you know that you have to do this, you should verify that your Media Access Control (MAC) address is entered correctly. A MAC address, or physical address, is an address that uniquely identifies each device on a network. A MAC address is a 12-digit alphanumeric value that appears in the following format: AA-A1-A2-A3-A4-A5. An Xbox 360 console, a computer, and a printer are examples of devices that can use a MAC address. The MAC address of a specific device is set when a device is manufactured.
To find the MAC address of a computer that is running Microsoft Windows 2000 Professional, Windows XP or Windows Vista , follow these steps:
a. Click Start, click Run, type ncpa.cpl, and then click OK.
b. Right-click Local Area Connection, and then click Status.
c. On the Local Area Connection Status screen, click the Support tab.
d. Click Details.
e. On the Network Connection Details screen, the MAC address of the computer appears next to Physical address.
To find the MAC address of a computer that is running Microsoft Windows 98 or Microsoft Windows Millennium Edition, follow these steps:
a. Click Start, click Run, type winipcfg , and then click OK.
b. Click the More Info button.
The MAC address of the computer appears next to Adapter Address.
To enter the MAC address of the computer in the Xbox 360 console :
a. In the Xbox Dashboard, move to the System section.
b. Select Network Settings.
c. Select Edit Settings.
d. Select the Additional Settings tab.
e. Select Advanced Settings Information.
f. Select Alternate MAC address.
g. Use the on-screen keyboard to enter the MAC address that you obtained from the computer.
h. Select Done.
i. Select Apply, and then select Test when you are prompted.