When the network is disconnected, the alarm will still go off but only if you are using default sound.
Besides, you cannot neither turn it off by voice command nor can you flip it over to snooze. You can dismiss the alarm by holding the screen, pressing the "Mute" button (round button) at the back of Vobot, or shaking the Vobot.
PS: You need WiFi to set up the Vobot and set an alarm. With Amazon Alexa service, you need to set the alarm by voice command which needs the Vobot to be Wi-Fi connected.