Yes, there's a few threads about it on the Billion forums (which, incidentally, I initially thought was about washing machines!), but nothing in the way of a solution.
I've asked on AVForums, but in doing so, I've realised that the machine (a Panasonic DMR-XW380) is older than I had realised, dating back to 2010.
Did Gigabit connections exist then? Even so, surely, if it was capable of showing data channels then (Vintage TV is what I'm trying to get) then it should be able to do so now. This, incidentally, is in addition to the failing of the Yamaha BD-S1067 Bluray (which, again, is older than I thought!) to play ball with YouTube, but I am assuming the issues are connected. Perhaps both devices are too old?