I was thinking the same. I had a lot of trouble last weekend particularly with the BBC i-player but also 4 OD. The i-player was continually buffering this afternoon even for radio which requires lower bandwidth. It automatically did a speed test which was close to 10 M/s. I then watched something on youtube without trouble.
I know that the weekend is busy time and it could be that the BBC site could not cope. Same could be true for other sites. I'm now watching a TV programme on it with no trouble at all.
If you have trouble with downloading for several websites do a speed check (as I said the BBC site does one automatically) and if low contact Virgin media.
Routers last about five years and Virgin had to replace mine a few weeks ago. That could be the problem.