The router has been replaced or the WiFi password has been changed.
Set up the WiFi connection again as follows:
- Press and hold the WIFI button on the remote control included with the robot vacuum cleaner until PaIR appears on the robot vacuum cleaner display. - The login details for the home WiFi network are reset. 
- Complete the pairing process for your robot vacuum cleaner in the app again so that the WiFi connection to the home network can be re-established. 
The robot vacuum cleaner is then shown as a connected appliance in the app again.
