hi Eccles -this happened to me a couple of days ago. The router in your box has to reconnect to the one plugged in at the wall (I'm talking abut WiFi) If you go onto the sky web-site it will give you instructions on what to do -usually pressing a button to reset the router but best go look for your particular model number
I don't have Sky but from my limited knowledge of these things this might (or might not) work. Switch off your router, switch off your Sky box and wait 30 secs. Turn your router back on followed by the box.