Black Hole
May contain traces of nut
I agree it's almost* the only reasonable conclusion, the trouble is: what, and how to fix it? The fiddling about is gathering evidence to try to work it out. As an engineer I don't like magic fixes, I want to understand the circumstances and why the fix worked, and the limitations of the fix (a random fix that just happened to work might be fragile). The EPG update problem is a case in point - we have found that a regular wake-up solves it, but what are the boundaries?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.