Check for noise on your line, 17070 option 2, best with corded phone. It should be silent between announcements. With a cordless you may get a dull hum.
Cn you post the connection stats (not status) from the hub, Advanced settings/technical log/information.
I have... BT Openreach tested the new line (installed 2 weeks ago) and found it to be, and I quote, "perfect". There is no noise on the line. We have been connected to one of the newest ports available in the cab and the engineer's tech team reviewed and confirmed the card's build / firmware versions.
Discussed the issue with BT via Twitter... <<sigh>>
I have also spoken to another BT user (on the same cabinet) who uses their connection throughout the day (wired to the hub - I know because I installed the PC) - they have stated they are also seeing these massive variances in actual service performance when using the web during the day exactly as I am reporting. I am providing the monitoring tools to them also.
This morning I have disabled the Wifi on my work laptop and moved to using a LAN connection (just to prove a point really). To quote my update to the Twitter conversation:
"Ethernet adapter & cable now installed. WiFi disabled on the laptop. First few tests show line behaviour (real performance) as previously reported regardless of negotiated line speed. Will perform full ping plotter analysis today."