I realise that I didn’t explain the level of severity, cone of acceptance thing, so let me rectify that. Line 2 is now perfect, that was the earlier killer problem referred to in the earlier emails from AA. It mysteriously fixed itself.
Now the current problem line, line 4, is either not syncing 95%, and that is over of the time, or very occasionally it comes up and syncs at 288-400kbps downstream with a ridiculous error rate. So it’s not remotely ‘marginal’ at all, the nice clearcult case that an engineer might like because there’s no doubt about it? Line 4 is effectively simply completely knackered: either dead, or worse. Note that I forced the downstream target SNRM up to 15 dB to try and keep the CRC / ES rate down to something tolerable, but even that SNRM that wasn’t enough to control the errors.
I’m now keeping line 4 disconnected so it can’t pollute the rest of the bonded set with all its CRC errors. Today AA said the only thing to do is to cease it and they didn’t offer to book an engineer.
Direct quotes from three earlier emails, as requested. Cut down for reasons of privacy and relevance / brevity. First email:
We have been trying for years to resolve this, and so far have failed to do so.
We don't admit defeat lightly, but I think it may be time to throw in the towel.
I think it's been clear for a while now that neither AAISP or BTW will be able to do any more than has already been done. This is of course not the outcome we wanted, and I'm sure neither did you, but we don't see a way forward.
Second email, excerpt:
[…]It's also worth mentioning, […], that any more fault reports will likely end in deadlock with BTW.[…]
Today’s email, which was extremely brief anyway, excerpt:
Line four is back up but in a very poor condition all we can suggest it to cease this line now.
A lot more detail would have been welcome in the first email, but maybe there are reasons why AA can only tell me so much.
A point about the other premises thing. Unfortunately I have no idea as I’m completely isolated. I never see anyone. I would have to ask Janet about neighbours’ experiences with copper lines. I don’t know how many neighbours use Openreach copper. It’s extremely dependent on which line you get. You either get a good line or a bad one. My line 3 is fantastic: 3.1 Mbps downstream sync rate and around 0.6 Mbps upstream.
Many recent HCD faults in the past were simply fixed by turning up and doing nothing other that running tests. Other faults were fixed by remaking joints, and this happened many many times. That seems to be the difference between a good line and a bad line: the joints you get.
For well over ten years with AA, or over fifteen years with DSL, my copper lines were reasonably reliable, with - I’m totally guessing, would have to many many review old posts - one to two faults per line per year. It looks like I get a lot of faults, but that happens when you have four times as many lines as everyone else.
Now for reasons unknown - was there a lightning strike ? - at the start of 2020, the storm of HCD faults began, and no one ever got to the bottom of it. The HCD faults were not confined to one line either.
So we had a good decade and a half and then three years of madness.