In the past month or so I've started to get very intermittent fibre, especially on my Mac.
Initially sites wouldn't load correctly and the router would drop out very regularly. I have now purchased a new router, a TP-Link VR900. My speed is seemingly stable and when the internet drops out it self connects again, something that wouldn't have happened with the plusnet router.
My speed via speedtest.net is generally very good with fast ping speed and 70+mbps. It just drops out all day long.