XBOX 360 Live - IP Address (Failed)

So Im trying to connect to the Xbox live, but I get this error:

IP Address (Failed)
- Your console was unable to negotiate a lease with your DHCP server. Make sure that addresses are available on your server.

Whattodo? D:

It means your settings have changed, or your router isn't designating your 360 an IP anymore. Your need to give details on how your 360 is set up. Network errors could be caused by anything.

As has been said, yeah, it means there's a conflicting IP address between your 360 and something else connecting to your router. They both tried to have the same IP and that's impossible so it doesn't work. Just unplug/replug your router and things should be fine.