Also, to exclude the possibility that the UDP network port is being used by your tv box, please try to temporarily change the port number that the message bus in the Launcher uses. You can do this as follows:
- Shut down the Launcher
- Open the file c:\Users[YourUsername]\AppData\Local\EpicGamesLauncher\Saved\Config\Windows\Engine.ini in Notepad or a text editor of your choice (replace [YourUserName] with your Windows user name)
- Find the line MulticastEndpoint=230.0.0.1:6666 and replace the 6666 with another number, i.e. 6345
- Save the file, and restart the Launcher
Please see if the problem persists with this change.