wireless can sometimes cause issues. There is so much 2.4ghz noise in the air, that its easy for issues to arise.

It is possible a neighbor got a new router and is on the same or close channel as you. Try changing the channel your broadcasting on. 6 and 11 are usually defaults. So being on 4, 7,8 are often the best.

You can use a program like http://www.metageek.net/products/inssider/ to scan to see what channels are open around you. and then pick the best option.