The best solution I have found is a powerline range extender kit which takes an ethernet connection from the router at front of house and feeds it into the electricity system, with wireless output from the electricity socket in the garden shed down the back garden. I wasn't sure it would work because the garden power is on a separate circuit, but it works brilliantly. If you don't have power in the garden then you need to look at a wireless relay to extend the range of your network