Xperia PLAY :: Wifi Not Working, But Connected?

Recently, we have changed our intertnet providers. Before hand we had AT&T, and when I was connected to wifi via phone it would work perfectly. Now though we have Cox for internet service. My phone is connected to the wifi, but more than half the time does it ever work. In small gaps am I able to connect to the internet with itOther times it's like I might as well not even be on. Any possible reasons?he wifi works fine for other devices in the house. Example as in my laptop. It connects just fine and am always able to access the internet.f my problem is confusing what is happening is that I am connected to the wifi and it shows I am. The wifi status icon is up and shows I have a connection. When I try to access a webpage or app that requires the internet, it will not load at all and sometimes say I do not have any internet access. So while it's "connected" I am unable to access anything and it's as if I'm not even using wifi.

Other details:We have a Motorola Cable Modem: Model SB121A Netgear Dual Broadband Router: Model WNDR3400-100NAS N600And for an extra secruity setting, we have selected the option not to broadcast the wifi so that the only way to connect to it is to know the SSID and connect manually.