Evening speed drops

[#1]

This relates to a new Plusnet FTTC connection, 40/20 unlimited option, installed on 04/11/14.
Using the TBB speed test, out of interest initially, and then concern at the variability noticed, speeds during the day so far have been pretty consistent at around 37Mbps down and 17Mbps up.  No problem with this and it runs as expected.
During the evenings however, the download speed drops to around a half or a third of this daytime speed, down to around 10 - 15 Mbps.
I have discussed this in a recent thread on Thinkbroadband in the Fibre forum (my first post in this thread: Wed 12-Nov-14 10:57:09)  Re: Plusnet Fiber traffic shaping ok for home work? :: Fibre Broadband :: think broadband
I was advised to run a few tests both via wireless and via ethernet to the router to indicate if it was an issue with the wireless connection,  I have done this and reported a series of tests yesterday, in the thread linked above.  It seems this steep drop in download speed in the evening is not related to wireless issues.
I would be grateful if Plusnet support could look at the discussion and those results as posted on the TBB forum.
My BT exchange went live for fibre in early October 2014 and this FTTC cabinet was available for connections a couple of weeks later.
My download speed this morning, using the TBB speed test, is back to 37Mbps, as on preceding days.
As I understand it this sort of speed drop is well out of the range of expected variation,  could support look into this please.

[#2]

Hi and welcome to the community forums.
I've had a read of that thread and the speed reductions you're seeing in the evening aren't what I'd expect. Can you run through the faults troubleshooter at https://faults.plus.net ensuring you answer all the questions, this gives us the starting point for a fault investigation.

[#3]

I would suggest this is not a "fault" - below is a SamKnows white-box graph from 23 Oct to today - 1Mbps horizontal grid. The largest spike is a 17Mbps drop at 21:00 on 11th November and is just one of a series that occur between 19:00 and 21:00. These match the max usage of Broadband bandwidth usage graphs closely. To me, that would suggest there are congestion problems somewhere (not necessarily Plusnet based) during these peak times.
For completeness, I am served by exchange THC.
Phil

[#4]

Having the fault ticket raised allows us to check for various issues, including common faults reported at the exchange or parent exchange. Any exchange capacity issues will show up more in the evenings as that's when more usage is seen (as you've noticed on the graphs), so it's always a good starting point to work from.

[#5]

@Chris
Didn't have that info in my "database" (though there appears to be some missing data - but the storage has been running continuously for nearly 71 years )
Phil