Ok, I have posted this issue on the BT Community Forum yesterday, but have so far had no reply, so I hope you don't mind me trying here!
A few month ago I gave up with my HH3 as wireless performance was poor and it kept dropping off some connected devices. I replaced it with a Belkin AC1800 Dual Band router as a) it stated it was for BT Infinity and b) I got a good price. It installed easily and I have been very happy with the wireless and wired performance. My wife was also happy as catch-up TV through Youview was consistently good.
That brings me to Tuesday evening and I thought I would look and see if BT Sport (subscribed channel) was showing any lead up to this weekends opening MotoGP race. It was only then that I discovered that I couldn't get any of the BT Sport channels and others like Eurosport. The message on-screen said that there was a problem with the internet connection. Obviously not, as catch-up TV works. Now I am sure that since installing the new router I have accessed at least one of the sport channels, but perhaps my mind is playing tricks.
So, searching for answers I keep coming back to the fact that these BT sport channels use Multicast and it needs to be enabled in the routers web interface. I cannot find such a setting in the Belkin settings so, with time running out does anyone have an idea of what might be needed to get back to 'proper' viewing (apart from re-installing HH3)
Thanks and sorry for the long post