Iphone wont stay connected to att uverse?? Help!?

[bp.]

So i really dont have the time or patience to call att and sit on the phone for hours trying to figure out what theyre saying. So a few days ago the wifi on my phone started going out. It'll work for like 30 secs then stop. Sometimes it still shows im connected and sometimes it doesnt. I have a very strong wifi signal in my house. I restarted my phone and the internet box but it still wont work!): its driving me crazy now!! We have had att fir a few months and had no problems until now. Has this happened to anyone? Ir any ideas how to fix?