Can't Download Anything With U-Verse WiFi

For the last couple of weeks I have not been able to download anything from the App Store and iTunes using ATT U-Verse internet WiFi at home on my iPhone 5s, iPad, and MacBook Pro. I have a 3801 HGV U-Verse GateWay with 20 Mbps download speed. It would take 2 hours to download something like Keynote for iOS and then the download would fail. Same thing for Music, Tv shows, movies on iTunes. Also can't stream movies or TV shows to my Apple TV and from iTunes on my iPhone, iPad, and MacBook. When I turn off the WiFi on my 5s and iPad and use Verizon 4G LTE everything loads fine and have no problem with downloading or streaming anything. So I know it's not a problem with my Apple Devices. I logged into the gateway and rested it and tried changing the firewall and security settings but nothing worked. All other downloads and streaming work fine (Netflix, PS3 Multiplayer, Adobe).

Anyone ever experience this? Know a fix?

Thank You!