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Broadband actual speed - Performance is getting worse. Line capped?

FIXED
Crellster
Hooked
Posts: 5
Registered: 09-09-2017

Broadband actual speed - Performance is getting worse. Line capped?

Hi, I'm on an ADSL connection 

Attainable Sync speed used to be around 4.5 Mb/s and it's dropped over the last few months to around 3.5 Mb/s.

I've been "living with" ~3.5Mb/s actual connection speed, but recently my line has become quite flaky.

Last week my connection seemed to be capping at around 3.1 Mb/s 

In the last few days it's now dropped to ~1.1 Mb/s (actual  - and still reporting ~3.5 Mb/s attainable),

 

 

Quiet line test is fine. 

LAN - 2ms response to my Router. 

PIng typically 33-40 ms - though it's been quite spiky in the last few days as well. 

 

 

I can kill all the clients on the LAN, so I know this is WAN side. 

Router Stats in the attached image. That's shortly after a reboot, but there are no HEC errors etc. 

 

Connection is: 

LAN - Ubiquiti USG - Billion 8800 AXL - NTE5a 

I have no internal phone wiring. . 

Have I been capped? 

Help Smiley 

10 REPLIES
Plusnet Help Team
Plusnet Help Team
Posts: 4,159
Thanks: 865
Fixes: 212
Registered: 21-04-2017

Re: Broadband actual speed - Performance is getting worse. Line capped?

Hello there.

From looking at what you’ve posted here, your speed doesn’t look capped. If you PM me your landline phone number if you know it I’ll be happy to run a line test for you.

If your sync speed is below your estimates shown at www.dslchecker.bt.com it may also be worth raising a fault to us at http://faults.plus.net


EDIT:

@Crellster

It looks like your speed is capped as the line is banded at:

Profile Info: WBC 576K - 1M Medium delay (INP 4) 6dB Downstream, UC Low delay (INP 0) 6dB Upstream (ADSL2+)

 

Line tests aren't identifying the cause of that. Is there any noise on your phone line when you dial 17070?

 

I'll also take a closer look tomorrow when I'm back in the office and can see your connection logs as if it's dropping then that may be the reason why it's banded. In the meantime, I've removed the banding for you now.

 

I hope this helps,

 

Anoush

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
Superuser
Superuser
Posts: 10,022
Thanks: 1,562
Fixes: 19
Registered: 22-08-2007

Re: Broadband actual speed - Performance is getting worse. Line capped?

A 52dB attenuated line might reasonably be expected to run at 4.5Mbps with a SNRM of 6dB.

Your SNRM is 9dB so 3.5Mbps is not unreasonable.

So the question requiring an answer is "What has been happening on your line to cause the SNRM to be 9dB?".  Gandalf notes that it is banded ... have you been bouncing the router a lot in an attempt to make it go faster?  We need to base line your line here...

What are the expectations for your line?

Please use the following links to check the services available and their estimated speeds. From the first link, please record and report back the distance from the exchange. The second link advises of which fibre services (if any) are available on your line and their anticipated speed.


 

 

Crellster
Hooked
Posts: 5
Registered: 09-09-2017

Re: Broadband actual speed - Performance is getting worse. Line capped?

Thanks both for responding and investigating. 

@Gandalf Openreach Quiet Line test seems absolutely fine, and I retested it again this morning. 

 

Something has caused the router to bounce at ~0901 today as I've now connected @ 3.5Mb/s - probably you lifting the banding I'm assuming? As I describe below I can also force a higher sync rate - which I've not been able to do for some time). I'll now monitor the stability. 

 

Can you tell how long I've been banded for - and whether I was previously on a higher band at around 3 Mb/s? That would explain what I've been observing. 

 

@Townman I've been a Plusnet customer for years and worked to squeeze every last bit of performance out of my copper tail and then pull back to something that offers stability first and foremost. My line's ability to support a higher sync rate has dropped over the last year or so. I was able to sync at @4.5 MB/s stably and consistently. I can test this by fixing the SNR on the line and testing the results on an unloaded connection. . 

 

 

Below are some tests I did when I upgraded my router in 2015 from a Billion 7800n to the 8800AXL. As you can see it's considerably higher than I can (could) achieve yesterday and recently. 

The router has been bouncing recently though I hadn't particularly noticed as I hadn't been checking (partly because it's always been stable). Lifting the banding has certainly improved things again. When the router has been disconnecting previously I would have tried to force a higher speed resync but I have not been able to do so. This could have forced the banding.

At 1237pm today I forced a resync and manually set the SNR at -5db to see if I could achieve a higher sync. The good news for me is that I can now once again set the SNR and influence the sync rate (connecting at 4003 Kb/s Smiley ) - something I haven't been able to force for some time. 

 

Could someone advise what the banding trigger is (disconnect count over what period of time) as I'd like to do some higher sync speed tests as well, but don't want to re-trigger the banding!

Many thanks!

 

Example sync speeds achieved on my line (2015)

SNR 5

-1dB

Line Rate - Upstream (Kbps)

793

Line Rate - Downstream (Kbps)

3600

 

 

SNR 4

-2dB

Line Rate - Upstream (Kbps)

797

Line Rate - Downstream (Kbps)

3815

 

SNR 3

-3dB

Line Rate - Upstream (Kbps)

804

Line Rate - Downstream (Kbps)

3894

 

SNR 2

-4db

Line Rate - Upstream (Kbps)

817

Line Rate - Downstream (Kbps)

4192

 

SNR 1

-5dB

Line Rate - Upstream (Kbps)

806

Line Rate - Downstream (Kbps)

4278

 

From <http://192.168.0.1/info.html>

 

SNR 4096 (Undocumented Values follow - see this post

-6.5dB

Line Rate - Upstream (Kbps)

821

Line Rate - Downstream (Kbps)

4370

 

SNR 4094

-8.5dB

Line Rate - Upstream (Kbps)

798

Line Rate - Downstream (Kbps)

5273

 

SNR 4093

-9dB

Line Rate - Upstream (Kbps)

824

Line Rate - Downstream (Kbps)

5095

 

SNR 4092

-10.5dB

FAIL

 

Returned to 4093 (~-dB

Line Rate - Upstream (Kbps)

812

Line Rate - Downstream (Kbps)

5515

 

 

Stable for approx 40 mins, then resynced to

Line Rate - Upstream (Kbps)

833

Line Rate - Downstream (Kbps)

4701

 

 

 

Superuser
Superuser
Posts: 10,022
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Re: Broadband actual speed - Performance is getting worse. Line capped?

I suggest that the above figures are not overly helpful.  A negative SNR is simply nonsense as would imply that the noise if greater than the signal and therefore not discernible.

I rather think that those negative SNR figures are the ADJUSTMENT which the router applies to the TARGET SNRM sent by the DLM on handshake.  Therefore to make a true assessment of those figures you would need to know the TARGET SNRM at the time of the tests.

Generally attempting to mangle the SNRM only leads to difficulty: there is the typical -2dB night time AM interference to be contended with.  On good lines you might get away with adjusting the SNRM down to 3dB if the target is 6dB ... anything more is I suggest asking for trouble.

@ejs has a fair knowledge on such matters...

Plusnet Help Team
Plusnet Help Team
Posts: 4,159
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Registered: 21-04-2017

Re: Broadband actual speed - Performance is getting worse. Line capped?

Something has caused the router to bounce at ~0901 today as I've now connected @ 3.5Mb/s - probably you lifting the banding I'm assuming?

Yeah, that'd be me.

 

Can you tell how long I've been banded for - and whether I was previously on a higher band at around 3 Mb/s? That would explain what I've been observing. 

From looking through the DLM profile data, the banding was placed on the 8th Sept 07:58. As far back as we can look, the circuit was in sync at 3.3mbps on the 27th August, steadily decreasing up until the 8th when it was banded.

 

Whilst the banding is now removed and the target SNR set to 6db:

Profile Info: WBC 160K - 24M Medium delay (INP 1) 6dB Downstream, UC Low delay (INP 0) 6dB Upstream (ADSL2+)

 

the SNR Margin is much lower than I'd expect, generating a considerable amount of errored seconds which will likely cause an intermittent connection and throughput issues.

 
  Upstream DSL Link Information Downstream DSL Link Information
Loop Loss: 33.1 52.5
SNR Margin: 6.0 1.6
Errored Seconds: 0 203
HEC Errors: 0  
Cell Count: 1538537 4135961
Speed: 864 4003

 

Could someone advise what the banding trigger is (disconnect count over what period of time) as I'd like to do some higher sync speed tests as well, but don't want to re-trigger the banding!

I think that's difficult to answer as it depends on a variety of other factors. Personally, I'd say 5 drops a day may cause DLM to intervene, depending how many days the circuit has been dropping for.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
Crellster
Hooked
Posts: 5
Registered: 09-09-2017

Re: Broadband actual speed - Performance is getting worse. Line capped?

Thanks @Gandalf I checked the connection stats and as you had guessed, it was a mess!. I'd had the same hunch as although the sync speed looked great, throughput was terrible. 

 

I forced a resync at ~1343 allowing the router to auto negotiate this time, rather than me forcing the SNR. 

However, download speed (actual) is still poor after auto negotiation. Ookla and another test are  showing ~0.9Mb downbload & 0.8Mb upload. The upload is fine but previously I would achieve over 2.8Mb actual download and often over 3Mb. Margin is ranging between ~4.2 and 4.8 currently as reported on Routerstats. There are no other clients on my network using bandwidth that could account for the impact (they are all disconnected).

I can see quite a few errors on the line as well - I reset the stats after the sync. (see "Stats after 30 mins on auto sync" attachment)

 

The other bit I'm still scratching my head over is what could have been causing the "steady decrease" since the 27th Aug to the point it rebanded again - though that's less of a priority!

 

Thanks once again.     

Crellster
Hooked
Posts: 5
Registered: 09-09-2017

Re: Broadband actual speed - Performance is getting worse. Line capped?

Hi @Townman those stats were really to just illustrate I'd previously been able to achieve much higher connection rates on my line. You are obviously right that a -db figure makes little sense and that is the adjustment from the target. I didn't think that would need explaining and they were just a cut and paste from some old notes I had. 

Whilst it's helpful to know the target SNR at the DLM, you don't need it. It can remain an unknown variable if you remain structured in the testing process. "Trial and error" may not be sophisticated, but it works...though you need to be mindful to avoid triggering banding.  

The critical parts for me were: 

1) What connection speed could I achieve at the exchange as a simple indicator. 

2) How does that translate in to actual  / sustained throughput on the line ... which is really all I'm concerned in optimizing and the part that took the time to get right because of the tradeoff between stability and throughput.

 

 

The tests with the larger -ve numbers were out of interest, and ultimately proved unstable on my line. I used a setting of -4 IIRC which is close you your assessment of the practical limit if the target was indeed 6db.   Smiley 

 

Plusnet Help Team
Plusnet Help Team
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Re: Broadband actual speed - Performance is getting worse. Line capped?

Fix

It looks like the speed profile on your account hadn't updated automatically following me unbanding the line over the weekend. I've just manually updated it now. Can you reboot your router and let us know how your speed looks?

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
Crellster
Hooked
Posts: 5
Registered: 09-09-2017

Re: Broadband actual speed - Performance is getting worse. Line capped?

Thanks Anoush. That's sorted it.
Plusnet Help Team
Plusnet Help Team
Posts: 4,159
Thanks: 865
Fixes: 212
Registered: 21-04-2017

Re: Broadband actual speed - Performance is getting worse. Line capped?

Yay. I like fixing things.

No problems, let us know if any further issues develop.
If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team