@Benjaminpurslow Depending on which sky Hub and booster matching set you have, then you may just have to move the booster close to that sky hub again, and re-pair them both with the wps button's, linked below the help.
Do take a look if you have the sky Broadband hub, someone mentioned that the wifi light was going off on there hub, if that is/was the case then the booster would not work as it would have no wireless wi-fi link back to it! Though not normal have seen the SE210 just lose connection and you have to just go do it all again, takes about 5 minutes to setup against each other, watch the WPS lights change state as the connect!
https://www.sky.com/help/articles/sky-wifi-booster-what-do-you-need-help-withbooster
