Something is opening incoming connections to your private network. If you look at the IP address of the device that its mapping to, you should be able to identify what application or program is doing it.
If you do not know what it is, the I would recommend that you disable UPnP on the home hub, for your own security.
I've been looking through my Smart Hub for the UPnP which you advise me to switch off. Is it on the Advanced Settings >Firewall> Configuration page. I found something on that page which says UPnP ON and then underneath it said Extended UPnP Security ON. Am i on the correct page, and if so shall i change UPnP to the OFF position then, leaving the Extended UPnP Security ON?