you can do three things in this order dude:
a) log into the shub @
http://192.168.0.1 and go into the wi-fi settings and make sure wi-fi is switched on
b) if everything looks ok pull the power cable out of the cable for a few secs and pop it back in. A reboot of the shub should kick it back into life.
c) if all else fails a factory reset will be in order by pushing in the little button. If you do do this all the shub setitngs will be wiped and you'll have to go back in and set your wi-fi passwords and all that stuff again.
Out of interest, have you got a shub 1 or 2. This kind of thing is very common on shub1, if it persists you can ring up and ask for another one, try and blag a shub2 (which is better) out of them or buy a proper router where you won't have this problem at all.