Reolink PoE NVR
You are able to set the PoE NVR to buzz (beep) when any of the cameras detect motion, which is sometimes an efficient way to alert you.
Go to NVR >> Menu >> Alarm >> Action, and tick Buzzer for selected cameras (channels).
Click Apply to save the settings. Untick this option if you don't need the NVR to buzz any more.