1. Check the cable connections and make sure everything is plugged in properly.
2. Make sure the TV is connected to the same network as the computer you are using.
3. Power cycle the router and the Smart TV and check both the modem and the TV for any errors.
4. Check the network settings and make sure the correct network is selected.
5. Check your router to make sure there is no blockage of any kind (hackers, censorship etc).