No signal/no connection/wireless

unless you have a 360 slim with the built in wireless, the only way to receive a wireless signal is a wireless bridge that plugs into your 360's ethernet jack on the back and that unit should be able to connect to the wireless signal. if it is a usb based
wireless receiver like for a PC then it will not work.

If your using wireless to connect to your network hardware try a wired ethernet connection.

You may be getting wireless signal interference.

A wireless ISP (ex. Sprint) connects through a wireless card over a cell phone network.

How the xbox connects is it connects through your wifi signal from your router. How your router gets the signal to send out doesn't matter. So, rather than plug your xbox 360 into your router, it connects through the signal it broadcasts. It is using your
same internet connection.

Sounds to me like it's an issue of wireless interference and/or poor wireless signal. If it happens again, try a wired connection.

is your connection wireless or wired?

if wireless, are there any electronic devices that could be interfering with the signal from/to your router?