I have BT Infinity 2, last tested at 74 meg down and 21 meg up, BT Hub 5, BT Youview box connected to the hub via BT extenders and last night iPlayer buffered at the beginning of a program and again near the end. I also have occassional issues with my home network losing connections between computers/printers/NAS drive, all of which are wired. I also obviously have several wireless devices using the Hub but at the time of the buffering most other devces in the house were idle.
I've checked everywhere I can to make sure network adapters in PC's aren't going to sleep but problems persist. My wife works from home and relies on a stable network and internet connection so guess who gets it in the neck when Call the Midwife starts buffering!
For me getting the HomeHub5 solved my problems. BT obviously weren't letting on that the HomeHiub3 was a dog, but it was! So, sorry, I can't help here. I suggest it's a different problem to the one here we all suffered.
When you talk about being connected via 'extenders' - do you mean homeplugs?
If so then I know these powerline devices can be somewhat temperamental. Have you tried resetting them and are they connected directly to the power socket and not via an extension block?
Can you try with ethernet cables directly from HH5 to YouView box?
Worth a look at:
I have exactly the same problem. Averaging 74meg down and 19 up on a BT Hub 5.
Until recently I had a 5 year old linksys on a 1.5meg line and iplayer streamed wirelessly perfectly with no buffering on a Panasonic smart tv. Now I have the 74meg infinity with a hub 5 iplayer buffers almost constantly.
Movies from the likes of Netflix have been fine on both infinity and my old 1.5meg broadband.
Yesterday I put in BT broadband extenders using high quality cat6 cables so the whole thing is now wired. The extenders are all working and the television and the extenders say all is well but iplayer is still buffering constantly.
Surely this has to be a problem with the BT home hub?!
(I am also getting it in the neck from my wife but it's Eastenders rather than Call the Midwife...)
Connect the Youview box to the HH5 via ethernet cable directly and see if that solves the problem.
What colour are the lights on your homeplugs? If they're all green, then everything should be fine. If they're orange or red you could have problems and that may be due to the wiring in your house.