Do you have Cable? If so, most likely it is because someone in your neighborhood is using it more right now then normal. Cable sells internet based on the speed they want to get you, not on the speed you can actually get. Also, it is a shared network and if they have a lot of people on you hub, it is like trying to pour a excess amount of water threw a funnel. As another illustration, ever flush a toilet when someone is taking a hot shower in some older homes? Then you understand Cable and your problem.