When the unit is switched on in a factory state without an Ethernet connection, it broadcasts it's own network. It is then waiting for you to connect to it and supply it with WiFi credentials. If the unit is not connected to a WiFi network, the Apple Airplay chip inside will tell the unit to power down.
As the product is designed to be connected to the network, once set-up you will benefit from Spotify Connect, Airplay and internet radio functionality as well as your primary Bluetooth function. Please make sure the product is configured with WiFi credentials or connected to Ethernet to prevent the product from resetting every 30 mins.