UPnP Discovery Service
When a UPnP device is added to the network, the UPnP discovery protocol allows the device to advertise its services to the control points on the network.
By enabling UPnP Discovery Service, the NAS can be discovered by any operating systems that support UPnP.
By broadcasting the network service(s) with Bonjour, your Mac will automatically discover the network services, such as FTP, running on the NAS without the need to enter the IP addresses or configure the DNS servers.
Note: You have to activate the services on their setup pages and then turn them on in this section so that the NAS will advertise this service with Bonjour.