This message is a warning that your charger has disconnected from your WiFi network.
The chargers do not rely on a WiFi connection for charging, and the majority of the smart features can be accessed via Bluetooth, which is why your charger is charging and the app is working.
The only feature the WiFi connectivity affects is the reporting of Charge History data because the charge logs cannot be stored on the charger.
To resolve this you need to reconnect your charger back to your WiFi network.
