Apple tv goes offline when I try to watch something on Netflix

Try this for any misbehaving app:

1. Update your Apple TV system software to the current version, if not done already.
2. Force-quit the app, then relaunch and try again.
3. If the issue persists, force-quit the app, restart the device, then relaunch and try again.
4. If the issue still persists, delete the app, re-download and try again.
5. If the issue still persists after that, then contact the app developer for further assistance.

have you tried to pull the plug on both appletv box and wifi router and let them start up again?