first .... back to basics
look on the back of the router .... what model is it?
either tell us ... or look here
http://www.dlink.co.uk/?go=jN7uAYLx/oIJaWVdDLg YU93ygJVYLelXSNvhLPG3yVjoUYppxu5vbMYkOfsxsXg6V HqqnHtD85pJVJ23gKHtOQ5A8ruEbIq3DNC89DUInMpMFP4 =
alternatively look in the bottom of your undie drawer for the book that came with the router.
remember the fix only works 'till someone else moves in who is also using that chanel
even better .... ditch the wireless ... use cat5 wire ... 100% interference free
or get a homeplug kit
either will end your problems for ever