Intermittent sync problem

I keep having intermittent sync problems with my 2wire 2701HG-B modem- the internet keeps cutting out every 5 minutes or so, then reconncecting. I cannot maintain a connection to a website such as Hulu or submit information via a button on a site such as eBay. I did set up a wireless network with a hardwired desktop and two laptops with the modem a couple weeks before this issue started. I do not believe that my internal house wiring is the issue, it worked fine for 9 months, and ATT ran an external line test that came back negative.