Not sure whether related, but watching Iplayer last evening, 9.30ish,was plagued with buffering. I'm on ADSL2+ and sync at 8367/815 kbps. Router to Freesat HDR is by Powerline adapter from upstairs BT extension. Pacing router by master socket is problematical, because of full occupancy of sockets and other bits 'n pieces.
Our Pinus Lofticus tree, that has to be located near the TV and HDR (available sockets) has two light strings; one older static, the other newer pulsating. They are plugged into a mature 4-gang extension, shared with TV and HDR.
So, I guess the opinion will be to blame router location, Powerline, lights, 4-gang extension in any chosen order. Thing is that I have watched IPlayer recently with same set-up at a similar time, and had no problem.
I suppose it could also be congestion and also may be have to think the combination of equipment is temporary; thus to be lived with.
That could be because I'm of some age with a wife who ails a the moment.