General Steps

1. Go to the settings on the TV / AirPlay device

2. Find the AirPlay settings

3. In AirPlay find an option to Reset Paired Devices

4. Reboot the Mac or Apple device unable to AirPlay


For the Samsung TV in the Art Lab

1. Press Home button on remote
2. Go to the left to open the side menu, scroll down to Settings
3. Settings -> All settings
4. Find Connections -> Apple Airplay Settings -> About Airplay
5. Click the Reset Paired Devices
6. Reboot the Mac that cannot connect to the Airplay