1. Check to see if the Smart TV remote app is connected to the same wi-fi network your TV is connected to.
2. Close and relaunch the remote app.
3. Double check that the remote device (i.e. phone) and the Smart TV are close together and there are no other objects blocking the signal.
4. Reboot the router and restart the TV.
5. Reinstall the app, if the problem persists.