I had to disable it to get Rhapsody software to work with my D-Link wireless router; but, I don't know why.
Universal Plug and Play - a family of protocols from the UPnP Forum (www.upnp.org) for automatically configuring devices, discovering services and providing peer-to-peer data transfer over an IP network.
Introduced in 1999, UPnP is not technically related to PnP (Plug and Play).
It is related by concept: both provide zero configuration, which is automatic installation without manual configuration