Humax YouView IP update address

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I have a Humax YouView PVR. It uses the internet to access the YouView servers to:

1. get thumbnails to populate the Recorded Programmes screen
2. update the Humax YouView s/w when an update is available.

I want to find out the IP address(es) that are used but having difficulty. I know the local IP address of my Humax box. I can apply a Display filter to just show the Humax. But all I see is local multicast/DNS stuff. I see nothing trying to get out to the wider web. Yet those thumbnails are there and if I unplug the ethernet cable, they disappear...so their display is effectively done in real-time.

So what am I doing wrong ?

The objective is to block the IP address used for updates.