New Fibre user, initially impressed but now somewhat disappointing speed

[#1]

OK I changed from Talktalk DSL to Plusnet fibre as i was getting hacked off with eroding speed.
The back story = A few years ago i got TalkTalk DSL and was getting a good 17Mbit download speed. Over a long period of time that slowly reduced to 9Mbit or so. I got suspicious thinking "are they throttling to push us over to fibre" so I canned TalkTalk and moved to Plusnet Fibre.
So I join Plusnet...after one engineer cancelling to install i eventuaally got one to come two weeks later (a BT engineer I think). So he installed my fibre, no problem, put his device on the line and showed me the readout, over 40Mbit....GREAT i thought.
Well, at first it was indeed pretty fast, speed test reading 35 Mbit or so even over wifi. I had an issue where my laptop wasn't connecting though but put that down to new Win 10 install and flakey drivers. Anyway I went on holiday for 2 weeks.
2 weeks on and its dropped to 20Mbit max. Why? This is barely any faster than the original speed I got with DSL a few years ago. If my line is capable of 40 Mbit why am i getting HALF of that AT BEST. Am i being throttled/shaped?
Plusnet support recently emailed unpromted - subject line "About your broadband speed". It outlined that my estimated speed was 17Mbps and line speed was 21Mbps. So where did the other 19Mbps go that the engineer showed me

Pretty disappointed tbh. My exchange is only at the top of my road between 1/4 and 1/2 mile away.

[#2]

Hi jetmaroo,
I've just performed some tests which show an obvious cause for this issue.
With that in mind please pop over to http://faults.plus.net and we'll get sorted for you ASAP.

[#3]

Adam im getting the same issue and in addition my downloads are failing and im getting buffering on streaming.
Call ref - #110747899 - Can someone investigate?
dick:quote

[#4]

Hi Adam thanks for your prompt response.
I followed your instructions and did some tests concluding, as you did, that my speed is a little off where it should be. Line speed showed 48MBits/sec or so. A ticket has been raised so I await further instructions/info.

[#5]

Hi scottca,
It doesn't look like exactly the same issue and I can see one of my colleagues in faults is already dealing with this for you.
@jetmaroo
Automated tests have picked up the same tests I did so we'll get that reported with our suppliers ASAP for you.

[#6]

Just to keep you in the loop and wrap things up for now. I did some tests and as advised switched all kit off for an hour then rebooted the fibre modem and subsequently the router and got a much better speed wired.
I then went into my router settings page and boosted wifi speed and its now pulling 34Mbit over wifi downstairs from my router which is upstairs so Im happy with the outcome- thanks for your help!!
regards, jamie

[#7]

Glad this got sorted for you
Matty