How do I deal with this problem with my router?

I use a Linksys router, and the signal just dies all of a sudden. We always have to go downstairs and unplug the router from the wall and re-plug it, and then it works again, but running up and down the stairs sucks. This has been happening for at least one and a half years. I’ve had enough. How do I fix the problem? I know it’s not a software problem because we’ve contacted linksys a bunch of times, and the problem continues. Linksys support is useless.