I've been having a similar problem with my Virgin Media fibre optic connection. I found that all my troubles were due to their so called
"Superhub". My iPad, iPhone and Apple TV were constantly buffering to the point where I just stopped using them on my home connection. VM sent me a new hub which was slightly better with new firmware, but it was still a rubbish connection. So I've replaced their Superhub with a NetGear N600 Dual Band Gigabit router and now my connection rocks! My Apple TV now streams HD program's without buffering and my phone and pad are seeing over 40mb while my laptop is getting 60+mb wired.
Fibre optic is great, it's a shame that these companies hand out cheap routers to access it with, and then just keep patching up the problems with firmware updates. VM still won't admit they have big problems with the SH, even though their forums are full customers who say otherwise.
Good luck and I hope you get yours sorted out soon.