Hello Mkevinm,
Thank you for participating in the Apple Support Communities.
It sounds like your iPhone and iPad Air are not able to AirPlay mirror to your Apple TV. Testing your network and ensuring the devices are on the same network were good steps.
Here are some additional troubleshooting tips that may help:
If trying to AirPlay, or AirPlay mirror, to your Apple TV, ensure that AirPlay is enabled on your Apple TV as well. You can enable or disable AirPlay on Apple TV in the AirPlay menu: Settings > AirPlay.
From:
Resolve issues with AirPlay and AirPlay Mirroring from iPhone, iPad, and iPod touch - Apple Support
Additionally, be sure to restart all of the devices:
Restart or reset your iPhone, iPad, or iPod touch - Apple Support
How to restart your Apple TV - Apple Support
All the best,
Jeremy