Setup for Streaming Devices

Got U-verse two months ago. I have a wireless Gateway for home internet, Motorola NVG589.

I had no problems what so ever the first month, but once my first month was over the router all of a sudden stopped allowing my mobile devices to access google related reservices. 

Both mine and my wife's phones can't even play a youtube video, stream, download apps on Google Play, surf non-slowly on mobile Chrome, or access Pinterest. Same for the tablet and ChromeCast. All worked fast and without error for at least a three weeks solid then nothing. Chromecast is completely non-operational because of the what the router is doing. I know it's the router because I've restarted, wiped clean, and reinstalled the phones and tablets, as well as exchanging the Chromecast through Best Buy with a new one. Nothing. Same problems.

Has been happing for about two weeks now. If it doesn't get fixed without me having to pay for a tech to come out here I'm going to switch back to Time Warner. Our devices worked fine with them. 

Thanks for any help you can give me.