In Alert Mode you can control the alerts when device and phone app get disconnected. You can control the audio alerts from the physical device and notifications from your phone.  

Step 1

Open the Nut app. Tap on 'Alert Mode' to go into the settings. Make sure it's turned on

Step 2

Turn "Device Alert" on and select the period that it'll be on for, as well as the duration.

Step 3

Turn "Phone Alert" on and select the sound the phone will make, as well as the duration.