Ok, so the engineer has just been - very pleasant chap and was as helpful as he could be, but as everything is running normally at the moment he believes the problem is much further up the line. He measured my light source which was 14.4 and will report everything upwards.
One thing he did notice though was that my speed test results vary quite considerably - one test when he was here was 210Mbps, then the next was 279Mbps. He said he would expect the speed to be fairly constant on FTTP given that I have a single fibre going direct to the exchange.
Does anyone else with FTTP get huge variances? Mine typically range from 150Mbps to 290Mbps (on BTW speed tester) and I always put it down the fact that at peak times the speed can be affected.
Next step in terms of the original issue is to call back when it next goes down...
Started to notice some stuttering when watching HD videos on YouTube so ran a few speed tests:
1831 - 95Mbps
1832 - 145Mbps
1834 - 215Mbps
1836 - 177Mbps
1836 - 101Mbps
1837 - 96Mbps
1838 - 147Mbps
1839 - 138Mbps
1840 - 168Mbps
1841 - 200Mbps
Quite a lot of variation and nowhere near the 300Mbps it should be.
I've not seen such big differences on mine in such a short space of time - but I do see what was my expected 70ish mb download speed earlier today is now testing regularly at 25mb this evening (and this is using both speedtest.net and the BTW speedtest).
And I'm back down to virtually nothing again and guess what, at 11.22pm there is no-one I can call to investigate the problem. I wouldn't mind, but I'm paying the highest charge BT offer.
Last test is below:
A few more tests, for what it's worth:
2329 - 2.22Mbps
2231 - 24.08Mbps
2332 - 32.95Mbps
2333 - 29.86Mbps
2334 - 30.83Mbps
0001 - 23.57Mbps
In all cases, upload speeds where 25Mbps or above and ping was less than 30ms.
And the results from Speedtest.net show something odd. When testing the server nearest me (Milton Keynes) I get:
Note that it says the server is circa 150 miles away. For some reason, Speedtest.net is defaulting to Leeds as my nearest. Speedtest normally works out your nearest location.
When testing a London server I get:
Testing a Leeds server gave 225Mbps down and 21.73Mbps up with a ping of 15ms.
A BTW test just now (0029) gave 6.10Mbps.
I'm not looking for anyone here to provide answers (unless you have them!) but it's useful to share my experience and there may be something here than can help BT identify the root cause, if they ever read this thread.
Ok the slowdown is happening again - so just for info on testing I'm getting between 0 to 0 .6 download on BTW speedtest, but speedtest.net is still showing my download speed as 60mb (and this includes MK server, as well as switching to Amsterdam). Upload speed and ping are normal for my Infinity 2 on both tests (around 20mb and 20 ping). So I seem to get normal results on speedtest.net regardless of server and regardless of my actual speed, if that means anything.
Speeds are still down low - 49.13Mbps at 0958 this morning.
Using the Ookla server in Amsterdam gave 223Mbps down and 21Mbps up (ping 16ms).
@ sendmark - what do you get if you use the Namesco server in London on Speedtest.net? My last test on that server gave 25.15Mbps down, 28.26 up (ping 14ms).
One odd thing though, when trying to run further diagnostics at BTW, I get the following: