1. Make sure that your phone and Smart TV are connected to the same local Wi-Fi
2. Check that your Smart TV is not muted.
3. On the Smart TV, go to Settings > General > External Device Manager, and make sure Remote Device and Wi-Fi Direct are both enabled.
4. Turn off the TV and back on again if possible.
5. Close the app and restart it again from the Home screen.
6. Check for any updates to the app, as well as the TV’s firmware.
7. Try with a different phone, as it might be an issue with the phone you are using.