There's a lot on the web about setting the Smart TV's DNS to 22.214.171.124 for a test.
If that doesn't clear it up let the maker fix their product or return it to the store as defective.
I recently upgraded my comcast service to X1. All devices in my house capable of streaming Netflix and other product work great (iPads, PS3, etc). gggggggLG TV and an LG DVD used in another setup refuse to stream now. In fact, I can get a connect wto the internet with both of them but no data is flowing, cannot even get data from the google site, so it is just not Netflix.
I contacted Comcast Tier 2 support, they opened all the IP address ranges needed and actually manually punched in the IP address for the the TV. Nothing works, any ideas??