I am on Vivid200 speed after an upgrade last year. I posted at that time, saying speeds were very slow, averaging around 50mbps and would only improve if I rebooted the modem and router, and then only for a while.
It was investigated and an engineer called who made adjustments at the road cabinet which made things better for a long time.
it seems recently that very similar conditions have returned (not sure if same thing or different, but similar conditions). I recognise that it is 'up to' and speeds do slow in busy periods, but when it it regularly around the 50 mark even at non peak, I would appreciate that t if you could investigate again to see if there are any issues such as before or other causes.