Kiosk requires a working Wi-Fi connection. It's highly advised to have a dedicated Wi-Fi password protected network.
Please, don't use hotspots provided by your cell phone to operate kiosks.
Should "No internet connection" message appear, close the kiosk app and open Wi-Fi network settings in Android. Check if Wi-Fi status is shown as "connected".
Double check the network connectivity of the Wi-Fi network using alternative device (say your mobile phone).
Restart the kiosk app.