Help - Apple TV app on Panasonic Smart TV - no connection.

Help - Apple TV app on Panasonic Smart TV - no connection.

Hi - my Panasonic Smart TV has Apple TV but today it now doesn't connect - it says "Could not connect to Apple TV, check internet, try again"

I have recycled power on TV and router, have checked TV software and disconnected TV network and reconnected and have deleted and reinstalled app on my phone.

I'm out of ideas! Short of a sledge hammer can anyone help?