Why can't I use iPhone/iPad Airplay to mirror to the ViewBoard screen?

Please make sure the Device is on the same sub-network as Apple Airplay can only support the same sub-network, if you cannot see the device name, (Cast-XXXX), you are on a separate Wi-Fi sub-network.

Can I use Airplay to mirror to a ViewBoard screen on a cross subnet?

Yes, please use vCastSender iOS and key-in the on-screen connecting PIN code. Then, on the iOS device, open the Control Center and touch AirPlay Mirroring.   You should see a device prefixed with “Cast-XXXX”, select it.   Enter the “AirPlay Password” to mirror your iOS device to your ViewBoard.