This means your air cooker or airfryer is not connected to your home WiFi anymore. You might have changed your home WiFi network and need to set up your appliance again.
Air Cooker:
Start the WiFi setup process by entering Tools → Settings → WiFi Setup on your appliance and follow the on-screen instructions.
Airfryer:
Make sure, your Airfryer is a connected model: HD9255, HD9280, HD9285, HD9880.
To start the pairing process, start the setup directly from the settings in the HomeID app or follow the steps as described below to start pairing with your airfryer:
HD9255, HD9280, HD9285: long press the temperature down button and follow the instructions in the app.
HD9880: go to Settings → WiFi Settings → WiFi Setup mode, then follow the instructions in the app.