If you have iOS 14 or later installed, it is necessary to enable Local Network access in your iPad or iPhone's Settings app in order to see your WiFi connected device. If this setting is disabled, ForeFlight will not be able to see your device.
To update your setting, open the iPad SETTINGS APP and select FOREFLIGHT. Turn the switch ON next to LOCAL NETWORK.
Image 1. Local Network Setting in Settings App > FOREFLIGHT