Does plusnet isp throttle there fibre connection?

They don't throttle in the conventional sense of the term but they do deploy traffic shaping quite aggressively. This differs from throttling in that it slows down individual connections based on protocol as opposed to slowing down your entire line. So for example, if you are web browsing and torrenting at a time of peak demand your torrent will be slowed down but your web browsing will still be at full speed.

I've been with them a number of years and I have to say I like this policy: it means your service behaves predictably. Real time traffic such as gaming, VoIP or web browsing always gets through in a timely fashion without being delayed by that huge amount of torrenting your next door neighbour is doing. Sure, your own torrents in turn may take a little longer but does it really matter if something takes five hours to download instead of four? I'd much rather not be kept waiting for web pages to load.

Plusnet Traffic Shaping

If your utilising a router, that is your situation. That is exactly what happened to me and as quickly as I disconnected the router and just used charter's Cable Modem, things have been working exceptional. Routers more often than not last for about 3 years after which it's time to change them.