The TV remote should have a 'Internet@TV' (or similar button). I had exactly the same issue but I got around it by connecting my Blue-ray DVD player (also Samsung) to the LAN instead of the TV and lo and behold ... it worked!!
I cannot connect to the Internet trough my smart tv - model number le40c720. I have connected via the Samsung dongle and completed the network test - all four parameters are ticked (Mac address / IP address / gateway ping / Internet service test ). It says at the bottom that my network is operating properly.
However, when I click on the internet@tv button I cannot access anything. Both the Samsung App and the Settings buttons are inactive (they appear in grey). I have reset the tv, reset the modem, connected via Ethernet, connected directly to the modem, adjusted settings etc but all still without any success.
Any guidance would be very much appreciated. Thanks