My FTTC 80Mbps Profile is still decreasing - It is now <30Mbps

[#1]

Hi, possibly one from Plus Net
Is it possible to reset my profile, when I was at 44Mbps it was fast and stable with no delays in loading pages or downloads, but intermittently my profile is reducing see below .
Before I went on to the 80Mb FTTC trial I was having issues with my ADSL connection (intermittent speed drops mainly at weekends – see my PN tickets) and it was suggested that by going to fibre all the problems should disappear.
However, as each week goes by, my profile has slowly decreasing from 44bps down to only 29Mbps now, at the rate of about 1Mbps per fortnight, but in jumps, it would stay at a speed for about a fortnight, but then suddenly drop and this has continued intermittently since I first went on FTTC.
I am some distance from my cabinet and I suspect there is still an issue with my twisted pair, but if my profile can be reset every few months, then so long as it does not get any worse I can live with it.
Can PN see anything on my line that is cauing this and can PN please reset my profile so that I can get what was a stable 44Mbps for a while please.
Dave

[#2]

Mine has also gradually decreased since switching to 80/20 at the beginning of the 80/20 trial, the largest decrease being the first one a few weeks after the changeover from 40/2 which also introduced extra latency, since then it has been much smaller drops but I'm down from syncing well over 70mb/s to under 60mb/s now.
Mine generally remains reasonably fast and responsive for everyday use but has lost a little of the original 'snappiness'.
It looks like the most likely cause for this is 'crosstalk' as more lines are enabled for FTTC from my cabinet (though it could be a line issue as I had a serious intermittent noise issue on ADSL2+ previously which was never solved).

[#3]

Bump - Can Plus Net please comment
Or shall I raise a ticket

[#4]

I suggest you are being unfair expecting a Plusnet response within an hour of them starting work (the team monitoring these forums don't work weekends) - especially when this morning there are significant problems with users usage not being recorded and monthly usage not resetting!

[#5]

Clearly you are better informed about PN's working hours and other issues than most, but I was not expecting a reply within an hour as you claim, I was just bumping my post to the top of the list so that they would see it and it would not be lost.
If you are so well informed, maybe rather than just criticising other people for the alleged shortcomings, why don't you try to help with useful suggestions instead.
I try to avoid forums these days because there is always some clever dick that has nothing useful to contribute, but just wants attention !

[#6]

http://community.plus.net/forum/index.php/topic,218.0.html#post_bump

[#7]

Hi Dave.G6HNI,
I can see that you have raised a fault, our faults team are currently testing your line and will update your faults ticket as soon as they have the results.
Apologies for the delay in response, the Digital Care team are not in over the weekend. If you need anything further chasing up then please let me know.
Chris
@w23
Is your connection wired or wireless? Try a wired connection if possible.
If your are still low, I would suggest raising a fault at http://faults.plus.net and complete the diagnostic questions so we can look into this further.

[#8]

@chris, mine is purely a reduction in sync speed since install and I think this is fairly common as more lines become VDSL2 enabled causing an increase in crosstalk so probably not really a fault, just a consequence of other people using my cabinet.
Throughput is currently OK for the sync speed so I'll not raise a fault unless things get significantly worse - to be honest the FTTC is so good I only know it's 'slow' by doing a speed test.

[#9]

Quote from: Dave

Before I went on to the 80Mb FTTC trial I was having issues with my ADSL connection (intermittent speed drops mainly at weekends – see my PN tickets) and it was suggested that by going to fibre all the problems should disappear.

Given that your line does appear to have some sort of fault whether it would have dissapeared by going to FTTC fibre depends on where the fault is.
If the problem was between the exchange and the local distribution box - green street cabinet somewhere near to your property then indeed going to fibre would have solved it.  This is because the BB signal now goes by fibre direct to the new fibre box alongside the existing street cabinet and only after that does it use the existing phone line.  Under FTTC the part between the exchange and the cabinet is no longer used for providing the broadband service to your house - but still is of course for landline voice call
If however the fault lies between the cabinet and your home, as this portion is still used by the FTTC Broadband service then switching to fibre would have no effect whatsoever at all on your problem.  In fact it might even make it seem worse.  As each new technology comes along (ADSLmax, then ADSL2+, then FTTC fibre) each progressively 'works' the line harder and harder at ever higher frequencies. So a minor unnoticeable fault on the ADSLmax service becomes more obvious and troubling on say the ADSL2+ service and so on.

[#10]

Thanks to all that posted useful info, unfortunately my Green cabinet is several streets away (approx. 500m), I am the last property on my exchange and I suspect the fault is in the bit between me and the cabinet
However, now that I am on FTTC, I no longer suffer from the regular, 4 weekly drop outs and very slow connections, that I was getting on ADSL so it is definitely an improvement, but at about the same rate that I was previously getting issues I now see my profile drop and it does not seem to recover like it did no ADSL.
I’m sure that if it can be reset every 6 months or so I will be able to stay above 30Mbps
I see on the ticket an initial status page and this line caught my eye...
Profile Name 15M-30M Downstream, Interleaving High - 4.2M-8.5M Upstream, Interleaving Off
So does that mean I’m on the wrong profile

[#11]

Hi Dave.G6HNI,

Quote from: Dave

Profile Name 15M-30M Downstream, Interleaving High - 4.2M-8.5M Upstream, Interleaving Off

The profile that you can see in your line test results is the profile that is currently set for your port on the RDSLAM within your local cabinet.  That profile will allow a downstream sync rate of between 15Mbps and 30Mbps (15M-30M Downstream).  The profile configured is totally controlled by BT's Dynamic Line Management (DLM) system.  For the profile to increase to the next level and allow a sync rate higher than 30Mbps your line will need to max out the 15M to 30M band (i.e. sync at 30Mbps) for a period of time (there are no official figures on this but it appears that this occurs within around 5 to 10 days).  
As line conditions fluctuate occasionally your sync rate and line profile will change, especially if your maximum stable sync rate sits on the threshold of a particular profile and the one above/below it.  As previously stated, everything in this regard is controlled automatically by DLM and so there is nothing we can do to manually intervene.  As long as your line is performing close to your line estimate I would recommend allowing the DLM to choose the best setting for you based on line conditions.
Any questions, just ask.

[#12]

The problem you are encountering is that Plusnet (or any retail-level ISP) has no ability to alter the profile of FTTC customers - it is entirely under the control of Openreach. They will only reset the profile at the request of an engineer attending your property - and even then, they don't always do it.
The Openreach cabinets have a list of profiles that can be applied to each line - starting with higher speed profiles without interleaving, and dropping from there (either adding additional amounts of interleaving or reducing the speed range). If the cabinet detects "problems" on the line (usually by seeing synchronisation problems, or by seeing a large-enough rate of CRC error-checking failures), then it will drop you down a profile level. If, during a period of monitoring your line, it encounters very few "problems", it may then bump your profile level back up again.
My experience is that it will drop the profile level sometime around 5-7AM on the day after the "problem", and it can be a month or more for it to decide to bump you back up again.
My experience is *also* that, when the profile change causes interleaving to be added (or increased), then the latency increases and the usable throughput drops.
We recently encountered a problem with our line, where there was a problem with the internal wiring, causing the phone to ring non-stop. It didn't cause a loss of sync on the VDSL connection, but it obviously introduced some detectable faults. At 5AM on August 6th, the latency increased from 12.2ms to 20.2ms (indicating that interleaving was turned on). Speeds dropped from 73Mbps to 69Mbps. We took a couple of days to sort the problem out, but it wasn't until 5Am on August 28th that the FTTC profile changed, and latency dropped to its previous value. Then it wasn't until 6th September that the speeds recovered to 73Mbps (with a resync around 7AM). I've attached a graph showing this...
Now, by "problem", I mean things that could be *real* line problems but also *any* amount of interference. And one main source of interference is the other FTTC customers being commissioned.
In your case, it likely means that you do have some kind of line problem, but that you may also be encountering interference from new subscribers being added. Certainly that would explain the behaviour where you see step-shifts in your profile at relatively long intervals. Unfortunately, you probably *are* on the right profile for the conditions that your line is currently encountering - after all, it is the presence of bit errors on the line (and that rate at which the errors occur) that causes the change in profile. If your profile was reset, it would probably drop to the current level within 2 days, not 6 months. If you want to improve the profile, then you need to get rid of the errors...
Alex isn't quite right... it isn't a sync at the top end (30Mbps) that will allow the profile to bump up. It is the absence of bit errors on the line that will allow the profile recovery. BT definitely rate quality over quantity in that regard.

[#13]

Quote from: WWWombat

Alex isn't quite right... it isn't a sync at the top end (30Mbps) that will allow the profile to bump up. It is the absence of bit errors on the line that will allow the profile recovery. BT definitely rate quality over quantity in that regard.

I should have said that the reason it is about the quality (bit-errors) rather than speed is because the change in profile might not improve the speed - for example, a profile change might keep you on a 15-30Mb speed range, but change you from high interleaving to low interleaving - and so alter the latency instead.

[#14]

Quote from: WWWombat

Alex isn't quite right... it isn't a sync at the top end (30Mbps) that will allow the profile to bump up. It is the absence of bit errors on the line that will allow the profile recovery. BT definitely rate quality over quantity in that regard.

This is true.  The DLM process works by calculating an Indicated Line Quality (ILQ) value which can be either Red, Amber or Green (there are infact seven ILQ values but I won't go in to that!).  It does this by monitoring "mean time between errors" (MTBE) for both upstream and downstream and "mean time between retrains" (MTBR) aka re-syncs.  ILQ Red results in a negative DLM change.  ILQ Amber, no change.  ILQ Green, positive DLM change.
It's worth mentioning that if you aren't hitting the top end of your current line profile then it's unlikely you will see a change in throughput speed anyway.  For example, profile: 15M - 30M and a downstream sync rate of 25Mbps.  If ILQ is Green and DLM increases the profile to 16.2M - 32.4M then the line will almost certainly remain in sync at approximately 25Mbps.  Therefore, if you're not maxing out your current profile, it's not important.  
Edit: You may however see an improvement in latency with the removal of interleaving as WWWombat has correctly pointed out.

[#15]

OK, wow, I won't say that I understood all of that, but many thanks for all the very detailed posts.
I will read through them a couple more times to see if I can get my head around everything you are all telling me.
However, I don't understand why, if I was downloading at approx 44Mbps for the first 5 or 6 weeks without any apparent issues, then I can't believe that 29Mbps is now the best I can expect to get.
A year ago, before I had issues on ADSL, I was maxing out my line and syncing consistently at 8096Kbps and then when I went onto ADSL+2 I was able to sync at just under 15Mbps, but a few months later I hit an intermittent weekend problem, which I think was/is interference based, because the problem would always disappear at around 7pm on the Sunday evening, but as it was only 1 weekend in 4 that I was affected it was impossible to fault find.
Immediately after the interference disappeared I could sync at 14Mb, but as the months went by my best sync speed began to drop down to about 10Mb. At that point a BT engineer swapped my line at the cabinet which dropped it still further and also increased my attenuation from 39 to 45dBi which also reduced by SNR margin.
I put up with the lower sync rate for another month or two before upgrading to FTTC.
So here exactly 1 year later, almost to the day and I have hit possibly the problem again.
Plus Net want me to allow a BT engineer to do yet another site visit, but on a week day and as the fault only appears at weekends, I don’t see how he will find anything
n.b. I have no internal wiring I disconnected everything when I first had a problem 2 years ago and the line between my property and the pole was replaced by a BT engineer at the same time.