How can I improve my wi-fi signal? I have a wi-fi system but of late the signal seems to vary from low to good and excellent. On the low and good connection it fails to send or receive though I can access internet pages. What I can do? John Roberts, by email Don't read too much into signal strength meter readings but sudden and noticeable changes in Wi-Fi performance are often due to one of three things. The first and least likely is a fault with the router, or your wireless device, however this is fairly unusual and they normally either work, or they don't. Some models benefit from a full reset, back to factory defaults every six months but only try this if you have saved your settings and know your way around your routers setup menu. Signal strength can be affected by moving the router, new metal structures like radiators, pipe work etc, or recently installed electrical or electronic appliances in the vicinity of the router (microwave oven, TV and so on). However, channel congestion is easily the biggest problem, due to neighbours Wi-Fi systems, other wireless devices (keyboards, mice, cordless telephones, central heating controls etc). Changing the wireless channel often helps, and this is done through the router's configuration menu, which you access through a browser on a PC or other device connected to your network. Details of how to do this along with your router's IP address will be in the router's instruction manual. The trick is to find an unused channel and the easy way to do that, if you have access to an Android smartphone or tablet, is a free app from Google Play, called Wi-Fi Analyzer. This has a graphical display showing all nearby networks, and the channels they are using. On a Windows PC or laptop try NetStumbler (netstumbler.com) or Vistumbler (vistumbler.net) if you are using Windows 7 or 8. Apple has restricted the use of Wi-Fi scanning apps on iOS devices though a version of WiFI Analyzer is available on jailbroken iPhones and iPads for 99 pence.