My service provider told me that I would shorten the life of my router (Netgear DG824M Wireless) if I were to continue my practice of switching it off as a way of reducing our energy consumption. I had been in touch with their support staff over occasional brief interruptions in my broadband connection. Graham Rooth
I don't know of any reason why turning a router off should shorten its life. On the other hand, I had two routers die in about three years: I turned them off and they never came back on. I now leave mine on all the time, and stand it on Blu-Tack legs to get some air underneath. Routers consume relatively little power -- probably around 8-15 Watts -- but you could measure yours with an energy monitoring plug.