Sudden (but consistent) speed drop 19 July on - anyone else?

[#1]

Thanks.  Have connected a new router:
ADSL line speed (kbps): up 574 down 3065
Line attentuation (dB): up 34.4 down 60.0
SN margin (dB):                 up 6.0 down 10.8
Router in master socket.  No noise on line according to noise checker.  Distance of 4.9km is the distance by road (as followed by the cables).
Does this make any sense?

[#2]

Hi puzzeldoff,
It is a real puzzle!!
The Attenuation is better - down by 7dB - implying you've moved 0.6km closer to the exchange  in reality, that is more likely to be that the second router calculates the attenuation differently.  CRT can you post a full CLT report please?
The SNRM at 10.8dB rather suggests that the line is banded - if I'm correct, you are not going to see a meaningful 'picture' until CRT can sort that for you.
US is slower, though the SNRM is higher, which might also point to an issue.
Right now, I'd sit tight until CRT pick up this issue for you and confirm my assessment.
What is the 2nd router?  Is it new?

[#3]

Quote from: puzzledoff

Distance of 4.9km is the distance by road (as followed by the cables). Does this make any sense?

Well yes and no  It makes sense that if the distance is 4.9km then  An attenuation of 67 would be likely correct
and even with an attennuation of 60  (4.3km)  the bit that doesnt make sense is how you ever get more than 2.5kbps

[#4]

Thanks for the assistance.  Just to answer a couple of points:
Yes, it's a brand-new Huawei HG533 (the previous one was a Belkin).
And yes, I was getting 3.25 plus or minus a fraction consistently until this problem started with a rebanding (if that's the term) to 1-3 mbps on 19 July.
I'll do as you suggest and await support from Plusnet.

[#5]

That's brought the attenuation down by 7db....
Can we see how this is looking after a period of stability, say 24 hours or so?

[#6]

That's fine - thanks.

[#7]

Just as an update to this, Plusnet advise me now that "your speed is running within the acceptable limits that your connection will allow". 
Given that it was running (and has always run) at 3.2mbps but now runs at 2.5mbps, and only dropped because it was inexplicably banded, that's a curious answer - and it leaves me with a speed that not sufficiently usable.
Result?  Fibre - but not with Plusnet because for some bizarre reason Plusnet restricts the U/L speed to 1.9Mb on the basic fibre package (the only one available in this area).  I've also been left very unimpressed with the ridiculously long wait times calling Plusnet - far, far longer than anything I ever experienced with TalkTalk!
So it's off and away to another ISP for a better deal, with all the usual freebies, and another customer lost to Plusnet because the recent price increase enables people to get out of their contracts without penalty.  It's an odd market - makes little sense to me, but that's what happens when accountants are put in charge of companies!