If your ISP is AT&T, we recommend disable internet security by AT&T. A simple google search will show u how unstable AT&T security is and it block random websites, their tool is not efficient enough. We recommend using Norton or AVG security tools instead.  IF you dont do this, many services such as IPTV channels / Cathup / Movies may not work. 

Go to their Smart Home Manager app and click on the top right icon (the one that looks like a chat icon)

Request to have your Activemore Disabled. 

and then go to Settings and select App Preferences:

And then disable Internet security if you see it listed:

Now try attempt to play the same content u tried before and it will work! Eventual try restart the device.