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Broadband Speed & High FEC Errors

briarley17
Grafter
Posts: 39
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Registered: ‎21-01-2014

Broadband Speed & High FEC Errors

Hi,
Our download speed has dropped from around 800kB/s (6.25MB/s) to 300kB/s (2.34MB/s).
You'll also notice in the attached router details the extraordinary high FEC errors which are coming in at about 100,000 a second.
I've attached everything requested in the speed faults sticky.
Help/info would be appreciated.
Thanks,
Alec
14 REPLIES
Plusnet Help Team
Plusnet Help Team
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Registered: ‎01-01-2012

Re: Broadband Speed & High FEC Errors

I'd wager the drops shown below are the cause of this

Your speeds have been banded to between 2 and 4mbps and ultimately we need to get the drops sorted as these will be the main cause
Can you run through our troubleshooter at http://faults.plus.net?
We can then get this looked into for you
If this post resolved your issue please click the 'This fixed my problem' button
 Matthew Wheeler
 Plusnet Help Team
briarley17
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Re: Broadband Speed & High FEC Errors

For what it's worth, it would appear the whole road (or certainly several people) have been banded as I've checked their numbers on the BT speedtests.
I will run through the troubleshooter now.
PS. Please do remove the duplicates of this thread.
Community Veteran
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Re: Broadband Speed & High FEC Errors

all removed
Plusnet Help Team
Plusnet Help Team
Posts: 6,113
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Registered: ‎01-01-2012

Re: Broadband Speed & High FEC Errors

Thanks for that.
We'll get this looked into and we'll be in touch as soon as we know more
Apologies for any inconvenience caused
If this post resolved your issue please click the 'This fixed my problem' button
 Matthew Wheeler
 Plusnet Help Team
briarley17
Grafter
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Registered: ‎21-01-2014

Re: Broadband Speed & High FEC Errors

Went through faults troubleshooter last week and arranged to have an engineer come out this morning between 8am-1pm.
(By the way, the troubleshooter asks for contact details, then ignores them and uses account defaults it seems)
Have just phoned to check whereabouts as they have not turned up and apparently the system messed up and no one was ever scheduled to come... so that's a day wasted waiting around.
Will apparently receive a call to arrange a visit, presumably again, for a weeks time. (Certainly different to experiences with BT which is often next day visit.)
And as if it knew, our broadband is now playing up again.
In the few minutes it's been back...
Error Seconds (Local/Remote): 1,506 / 0 (interestingly this figure is over 25minutes? When line has been up 5 minutes? Unless this does not work out quite as literally as I'm reading it)
FEC Errors (Up/Down): 0 / 2,068
About an hour ago, up/down FEC errors were reading 0/2,882,566,405, with this number again rising at 100,000+ a second.
Speed is still down (for several properties on the road that I've been able to check, all plusnet), although up from last week at 400-450kB/s (3.13-3.52Mb/s).
I've attached a screenshot of the routers connection details page from yesterday.
Hopefully this is sorted soon.
Plusnet Alumni (retired) LinnPlusnet
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Re: Broadband Speed & High FEC Errors

Hi briarley17,
Really sorry to hear the engineer wasn't arranged for today as it should've been!
I've had a word with a member of our Faults team and they have confirmed that your new appointment is booked for 29/04/2014 between 8AM and 1PM.
Hopefully this will be resolved following the engineer's visit.
briarley17
Grafter
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Registered: ‎21-01-2014

Re: Broadband Speed & High FEC Errors

Update from the engineers visit this morning:
The engineer arrived and did his tests. Discovered our houes wiring was dreadful. Our 'master socket' ie the socket with the components of a master socket was not the first socket that the line came into the house at...
After crawling around in the eaves and rewiring some bits it's now directed to our lounge socket and the max line speed he measured as 13.5Mb/s 15.5Mb/s! Much faster than anything previously. The router stats also reflect this.
The FEC error issue appears to be fixed, with 0 since the line reset, although this is presumably helped by interleaving being removedHuh However we appear to be getting the same amount or maybe more of CRC and HEC errors which are more serious.
Also, the line speed is still down, although it would appear it's capped plusnet end? As current line speed in member centre says 4Mb..?
I have again attached speedtest and router details pages.
The engineer said to expect drops whilst the line configures in the first 10 days. The second screenshot of router details (shorter connection time) has a much higher HEC error number. This seemed to shoot up to 41000 odd at some point and is now steadily increasing.
If the line speed is being plusnet 'capped' could this be removed/increased to in the region of 13+?
Edit: Line has now synced at 15.5Mb so a 'cap' of 15.5Mb+ would be good!
Update: Engineer phoned thinking he'd left his mobile, phoned again to say he'd found it. Mentioned speed and CRC/HEC errors and he checked speed and got sync BT end at 13.5Mb, confirmed that it was probably a Plusnet cap. Also mentioned CRC errors being at 5000 after a couple of hours and he again said that was far too high, but if the line was stable, ie not disconnecting, and speed was up then don't worry too much.
Update 2: Phoned to have line speed lifted to 21Mb maximum Plusnet end.
Superuser
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Re: Broadband Speed & High FEC Errors

Hi,
The best synch speed that you can expect on your line - 31dB attenuation - is 14.5Mbps, which would give an IP profile (data throughput) around 12.8Mbps.
A synch speed of 15.5Mbps might deliver a profile of 13.6Mbps, which is what you might see on the PN profile after the PN systems have seen the update from BTOR.
You are not likely to get anywhere near 21Mbps.
briarley17
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Re: Broadband Speed & High FEC Errors

Hi Townman, thanks for the extra info.
BT speedtests have come back 12.59Mb/s and 12.31Mb/s and I'm more than happy with that.
The engineer got 13.5Mb whilst here and it's since synced at 15.5 this last occasion.
I was hoping to be back up to where we were at about 9Mb/s sync, so I'm pleased with the result!
And yes, I understand we won't get 21Mb/s, it's just one of the limits that can be set.
The only slight issue is CRC and HEC errors now.
Although CRC seems to have calmed down from over 5000 in just over 2 hours to 558 in 2h23m. (See screenshot)
But, as I said, the engineer wasn't too woried so long as the line and speed was stable.
Superuser
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Re: Broadband Speed & High FEC Errors

Hi,
You are working in the "twilight zone" for your line.  At 15.5Mbps you are pushing your line to the limit and you should therefore expect to see line errors, which can happen and are corrected / managed by the modem.  The acid test is the error rate so high that the effective data transfer speed is significantly diminished?
After you have confirmed that the PN speed profile has been updated to match your current BT profile, then it would be worth doing anther BTw speed test and see how close that comes to the profile.  If it is someway off and you have a noticeable impact on your BB enjoyment, then possibly the TARGET SNRM ought to be raised to 9dB to give your line more stability, yet still deliver a decent synch speed.
Remember a high synch speed with a marked error rate leads to a slower effective data rate.
Personally I'd keep a watching eye on this and leave the DLM to its job, as given all of the issues the BTOR engineer found, I would hope that he reset the line so that the DLM "returned" to its 10 day training period.
briarley17
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Registered: ‎21-01-2014

Re: Broadband Speed & High FEC Errors

BTW is getting around 12.5Mb/s, and in real terms I am also downloading at this speed (1.56MB/s).
I assume SNRM refers to 'SN Margin (Up/Down) [dB]:  6.0 / 2.9' which is it's current reading in my router stats, although I'm sure this will find a decent value over the next 10 days to keep the line stable.
The engineer did indeed reset the line to 'return' to the 10 day training period and said to expect a few drops as it works out what the line can manage with stability.
Thanks for your help and I think I'll do exactly as you said and keep a watching eye on it!
Superuser
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Re: Broadband Speed & High FEC Errors

Hi,
Your router is real persevering!  SNRM at 2.9dB is low-level flying!  But if it can hold that without an undue level of errors, then you are on a real winner.
If you want to do some detailed "keep an eye on it" watching, then download and install RouterStats from here - http://www.vwlowen.co.uk/internet/files.htm - and run it 24x7.  This will constantly record your SNRM (suggest that you log at 60 second intervals).  You can also consider getting the custom loggers to record one of the error counters.
I hope that you find that all is now OK for you.
briarley17
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Registered: ‎21-01-2014

Re: Broadband Speed & High FEC Errors

Thanks. I'll have a look at that when I get a second and will definitely leave it running.
It is now back up to 4.6dB. Speed is still as it was yesterday (12.92Mb/s on BT test).
All seems okay other than slightly high CRC and HEC errors.
I'll look into that program and start monitoring the SNRM and the errors when I can.
Thanks!
Superuser
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Re: Broadband Speed & High FEC Errors

Quote from: briarley17
I assume SNRM refers to 'SN Margin (Up/Down) [dB]:  6.0 / 2.9' which is it's current reading in my router stats, although I'm sure this will find a decent value over the next 10 days to keep the line stable.

Hi,
I forgot to provide a detailed reply to this question...  Yes SNRM is Signal to Noise Ratio Margin, which is a little different to SNR.
The SNRM might / can vary all of the time, the important thing to note is that the closer it gets to zero, the more difficult it is for data to be transferred without error.  Error correction (FEC / HEC / CRC) will always try to undertake data error recovery, but when it fails, there might be the need to resynch the link and start again.
When ADSL synchs up a line, it negotiates a synch speed which delivers a SNR Margin above the then present background (electrical) noise on the line at the TARGET SNRM set for the line.  Thereafter the synch speed remains static for the DSL session.  If the background noise rises, the (dynamic) SNRM figure falls and more errors might be encountered; if the background noise subsides the (dynamic) SNRM rises and fewer errors will be experienced.
Consequently you cannot look at the CURRENT (dynamic) SNRM in isolation and draw conclusions from it beyond the fact that the current noise level is different to what it was when the DSL session was commenced.  For this reason on a good line, one would want to initiate a new DSL session in the morning on a dry day to get the best possible synch speed.  Where as on an unstable (faulty ?) line, one would want to initiate a new DSL session after dark on a nasty wet night thereby attaining a synch speed at which the line will remain most stable.
In your case, it looks like you have a TARGET SNRM of 3dB (which is low and thus hopeful of a very stable line - ideal world view) and therefore you are getting a synch speed way above reasonable expectations for your line, but with a degree of errors.  provided the errors are not too high and you have a reasonable data throughput experience, I'd be smiling!