[MovedGoalPosts]

Another thought is whether you are getting a good wireless signal between your PCs and Router. Other electornic gadgets, Walls, Floors etc can all degrade the signal. Just because yo are theoretically in range doesn't mean it will all be at full power. You may want to experiement with the siting of the wireless components especially the router, whcih migh not work well stuck in a coner on the floor.