May contain traces of nut
I'll stick to what I said before, there's something iffy with your network.
When I move the HomePlug from the HDR I will have replicated the network conditions that were extant when the HD portal started running. I have already swapped the wires in the router. The HDR is fine. There is no reason for the router to treat the HD any differently because it is on a HomePlug instead of a wire, and yet it seems to. The MSP has no trouble phoning home, and there is no reason for the router to treat that external traffic any different from the portal traffic, and yet it seems to. A DS1000 swapped onto the same wire as the HD works on its own portal. Go figure. I'm pinning hopes on a factory reset at the router. I am thinking of buying a long Cat5 just to be able to connect the HDR in EXACTLY the same way as the HD and see what happens.
* there is still a niggle in my mind about the lack of an aerial connection. Apart from the network configuation, that is the principle difference between how the HDR and the HD is being operated. The DS1000 doesn't have an aerial socket in the first place. The HD worked when it did have an aerial. It all fits and is more rational than random router funnies.