I know it's annoying but if you can't find any superficial problems that are causing your intermittent connection, just wait. Usually it's that your ISP is trash or that they're doing repairs/upgrades around your house. If it continues past today, you should definitely call them and explain your problem.
Have you been torrenting a lot? I know that some of my friends get terrible connection issues like this when their ISP throttles them. If you haven't meh. Now if you've waited, called, not torrented, and it still persists it's probably on your end. In that case, you might actually have a virus creating high amounts of traffic on your connection or you router could be broken. There's a multitude of things that could be going wrong there.