Universal Plug 'n' Play (UPnP) is designed to make things a little easier for everyone. Whilst there have been issues regarding the potential for a security risk by using UPnP, it makes things much simpler when used.

Essentially a UPnP device will communicate with the sky Hub and provide the sky Hub with a list of ports that the particular device needs to be opened. This means that you don't need to worry about internal IP Addresses changing or setting up specific port forwarding services.

You can disable the feature if you desire.