Does your computer disconnect when you are plugged in directly?
Does this happen on multiple computers with the same router?
Has any new furniture or appliances been added to your location?
It is also possible that the router is beginning to go bad. This is the same thing that mine began to do and then it died soon after. Routers are one of the most difficult devices to troubleshoot, IMHO, and this could keep you busy for quite a while.