Recurrence of previous problem

[#1]

A month or so ago I had a problem with vey low upstream sync, sometimes as low as 90Kbps.  This problem eventually disappeared and for the last 3-4 weeks my line has performed well, downstream just over 3Mbps, upstream 448Kbps and not a single resync during this period.  A few days ago I started having resyncs resulting in low upstream figures again.  Forcing a resync would sometimes restore normal speeds but not for long. I now have 3.36Mbps down but only 192Kbps up.
RouterStats Lite is showing downstream SNR varying between 8 and 9dB, upstream SNR is solid at 7dB.
Can a Plusnet support person have a look at my line to see if there is any obvious problem?
Many thanks
HughA

[#2]

Hi there,
I can't see an obvious cause for this to be honest but I'm wondering if you might want to let us uncap the upstream to see if that helps with this issue maybe?

[#3]

Thanks Adam, I can't see that helping to be honest.
My long line probably won't support more than the 448kbps anyway.  I suspect some form of interference affecting only the upstream frequencies.

[#4]

An update to this.  Several more disconnections have happened and the DSLAM has raised my SNR to 12dB.  The disconnections are still happening though so I guess the SNR will soon be at 15dB.  The plus side of this is that my upstream sync is now steady at 448Kbps, the negative is that my downstream sync is down to 2656Kbps.  I'm busy all weekend so can't run any tests but on Monday I'll connect the router to the test socket and see if anything changes.  Several, but not all, of the disconnections have coincided with incoming or outgoing phone calls so I suspect a line problem somewhere though no noise is audible on the phone.

[#5]

Hmm. Are all phones filtered? If not that may well be the cause, but if they are then please try plugging a microfilter into the test socket with a single phone and see if the fault still occurs there?

[#6]

Hi Matt
Yes, phones are filtered.  No point doing any further tests at the moment as whatever was causing the disconnections seems to have stopped, none for 12 hours and using the phone no longer causes a resync.  Unfortunately my downstream is now down to 2.656Mbps as a result of the 12dB margin.  I'll try a forced resync now the line seems stable to see if I can recover some speed.
That's brought it up to 2.752Mbps with 448Kbps upstream.  If it stays like this for a few days I'll ask you to do a reset for me to get my speeeds back to normal.
The trouble with this intermittent problem is that it never stays long enough for any usefull faultfinding!  I wish the fault would recur and stay as there is obviously a problem with the line somewhere.

[#7]

Well if it's intermittent then I doubt it's internal (which was what I was hoping to establish with the test socket check - phone calls dropping connection can be indicative of an issue with the internal wiring).
We'd be more than happy to reset the SNR and let the line retrain, I'm not sure it'd be worth raising a fault unless it starts happening more often than currently though. Intermittent faults are indeed a pain.

[#8]

Yes Matt, it can be rock solid for weeks then plays up for a few days before sorting itself out for another few weeks!  I'm pretty sure its not a problem with internal wiring but I will double check at the test socket next time it occurs.  Hold off on the reset for now, I'd like to be really sure its stable first.  I'll request it later in the week if all is still OK.

[#9]

Well, the problem is still there.  Made a call this morning and the internet immediately disconnected.  I've moved the router to the master socket and sync is now 2.816Mbps down but only 320Kbps up so the problem is still there.  I will monitor for a couple of days but I think there must be a line fault.

[#10]

It's certainly looking that way. If you do go ahead, raise it through http://faults.plus.net - that'll take you through the relevant checks (most of which you'll have done already) and will pass it straight through to our faults team for you. Hope it gets sorted quickly.

[#11]

Fault raised.
Update.  Fault team reckon line to be unstable, engineer booked for Monday morning.  Hope they manage to track down this long standing problem.

[#12]

The good news.
OpenReach engineer arrived as scheduled, ran tests and decided the external wiring to the master socket was well past its use by date.  Apparently it was a copper pair and probably 30+years old.  He fitted a new master socket with filtered faceplate in a different room (better for me), with new, much shorter external wiring, then ran some tests and said all was well.  He also said my speeds would increase after an SNR reset which he would request.  My sync speeds increased significantly immediately, now 3200 downstream even with the 12dB SNR.
The bad news.
I'm still getting lots of disconnections.  I would expect this if the SNR reset had taken place (training period) but I dont think it has yet as SNR is still 11dB.  So I suspect I still have a problem.  Could it be the router? Its the only thing that hasn't been replaced, or is there another line fault lurking there?
What next?  Any suggestions gratefully received.