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uk.telecom.broadband (UK broadband) (uk.telecom.broadband) Discussion of broadband services, technology and equipment as provided in the UK. Discussions of specific services based on ADSL, cable modems or other broadband technology are also on-topic. Advertising is not allowed.

Sudden speed increase but poor reliability



 
 
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  #1  
Old February 19th 15, 12:32 PM posted to uk.telecom.broadband
Alex Fraser
external usenet poster
 
Posts: 553
Default Sudden speed increase but poor reliability

Hi,

Recently, my ADSL connection (Plusnet) has become very problematic, but
the symptoms seem unusual, and I wonder whether anyone else has
experienced similar and/or can suggest a cause.

Before problems started, downstream was around 6-7 Mbit/s with 3dB noise
margin. Interleaving is on, with some uncorrectable errors but not
enough to be noticeable.

I was aware of problems on Friday morning, which I subsequently
established coincided with the end of scheduled maintenance in my area.
Later investigation showed downstream was now 8.5-9 Mbit/s, but with
about 0dB margin(!). And as you might expect, many uncorrectable errors
and (sometimes lengthy) disconnections - an unusable connection, more
often than not.

On Saturday, after plugging the router directly into the test socket and
finding no difference after a few hours, I raised the matter with
Plusnet who did a "broadband reset" (not sure if this is their term or a
general one, but it sounds like the same "calibration" as happens when a
line is first activated; they said "may take up to ten days"): problem
almost instantly solved. I checked at various times and downstream was
in fact somewhat faster (around 7.5 Mbit/s) with noise margin varying
between 3dB and 6dB (part of the process Plusnet had initiated?),
settling on 3dB.

Great, I thought... until yesterday (Wednesday), when the behaviour that
had started on Friday returned.

Has anyone come across similar? Any thoughts as to what is going on?

Thanks for reading,
Alex
  #2  
Old February 19th 15, 01:00 PM posted to uk.telecom.broadband
Graham J[_2_]
external usenet poster
 
Posts: 723
Default Sudden speed increase but poor reliability

Alex Fraser wrote:
Hi,

Recently, my ADSL connection (Plusnet) has become very problematic, but
the symptoms seem unusual, and I wonder whether anyone else has
experienced similar and/or can suggest a cause.

Before problems started, downstream was around 6-7 Mbit/s with 3dB noise
margin. Interleaving is on, with some uncorrectable errors but not
enough to be noticeable.

I was aware of problems on Friday morning, which I subsequently
established coincided with the end of scheduled maintenance in my area.
Later investigation showed downstream was now 8.5-9 Mbit/s, but with
about 0dB margin(!). And as you might expect, many uncorrectable errors
and (sometimes lengthy) disconnections - an unusable connection, more
often than not.

On Saturday, after plugging the router directly into the test socket and
finding no difference after a few hours, I raised the matter with
Plusnet who did a "broadband reset" (not sure if this is their term or a
general one, but it sounds like the same "calibration" as happens when a
line is first activated; they said "may take up to ten days"): problem
almost instantly solved. I checked at various times and downstream was
in fact somewhat faster (around 7.5 Mbit/s) with noise margin varying
between 3dB and 6dB (part of the process Plusnet had initiated?),
settling on 3dB.

Great, I thought... until yesterday (Wednesday), when the behaviour that
had started on Friday returned.

Has anyone come across similar? Any thoughts as to what is going on?

Thanks for reading,


Can you repeat the problem with another router? Both a similar make &
model and something quite different?

If so, ring Plusnet again and they will send out an Openreach technician
to investigate.

The first thing this technician will do is to try to repeat the problem
using his own equipment. If he can't then he goes home and Plusnet
sends you the bill. So following Plusnet's instructions and testing
with another router (perhaps one they supplied to you) is essential.

--
Graham J



  #3  
Old February 19th 15, 08:19 PM posted to uk.telecom.broadband
Woody
external usenet poster
 
Posts: 750
Default Sudden speed increase but poor reliability


"Alex Fraser" wrote in message
...
Hi,

Recently, my ADSL connection (Plusnet) has become very problematic,
but the symptoms seem unusual, and I wonder whether anyone else has
experienced similar and/or can suggest a cause.

Before problems started, downstream was around 6-7 Mbit/s with 3dB
noise margin. Interleaving is on, with some uncorrectable errors but
not enough to be noticeable.

I was aware of problems on Friday morning, which I subsequently
established coincided with the end of scheduled maintenance in my
area. Later investigation showed downstream was now 8.5-9 Mbit/s,
but with about 0dB margin(!). And as you might expect, many
uncorrectable errors and (sometimes lengthy) disconnections - an
unusable connection, more often than not.

On Saturday, after plugging the router directly into the test socket
and finding no difference after a few hours, I raised the matter
with Plusnet who did a "broadband reset" (not sure if this is their
term or a general one, but it sounds like the same "calibration" as
happens when a line is first activated; they said "may take up to
ten days"): problem almost instantly solved. I checked at various
times and downstream was in fact somewhat faster (around 7.5 Mbit/s)
with noise margin varying between 3dB and 6dB (part of the process
Plusnet had initiated?), settling on 3dB.

Great, I thought... until yesterday (Wednesday), when the behaviour
that had started on Friday returned.

Has anyone come across similar? Any thoughts as to what is going on?



Don't worry, Uncle Bob will be along shortly to fix it 'from the
inside.'


--
Woody

harrogate3 at ntlworld dot com


  #4  
Old February 20th 15, 10:47 AM posted to uk.telecom.broadband
PlusNet Support Team
external usenet poster
 
Posts: 995
Default Sudden speed increase but poor reliability

On 19/02/2015 20:19, Woody wrote:
"Alex Fraser" wrote in message
...
Hi,

Recently, my ADSL connection (Plusnet) has become very problematic,
but the symptoms seem unusual, and I wonder whether anyone else has
experienced similar and/or can suggest a cause.

Before problems started, downstream was around 6-7 Mbit/s with 3dB
noise margin. Interleaving is on, with some uncorrectable errors but
not enough to be noticeable.

I was aware of problems on Friday morning, which I subsequently
established coincided with the end of scheduled maintenance in my
area. Later investigation showed downstream was now 8.5-9 Mbit/s,
but with about 0dB margin(!). And as you might expect, many
uncorrectable errors and (sometimes lengthy) disconnections - an
unusable connection, more often than not.

On Saturday, after plugging the router directly into the test socket
and finding no difference after a few hours, I raised the matter
with Plusnet who did a "broadband reset" (not sure if this is their
term or a general one, but it sounds like the same "calibration" as
happens when a line is first activated; they said "may take up to
ten days"): problem almost instantly solved. I checked at various
times and downstream was in fact somewhat faster (around 7.5 Mbit/s)
with noise margin varying between 3dB and 6dB (part of the process
Plusnet had initiated?), settling on 3dB.

Great, I thought... until yesterday (Wednesday), when the behaviour
that had started on Friday returned.

Has anyone come across similar? Any thoughts as to what is going on?



Don't worry, Uncle Bob will be along shortly to fix it 'from the
inside.'


It's relatively trivial for me to submit another SNR reset (I'd just
need some method of identifying your account). It is fairly odd that
things seem to be going south over time rather than north though.

If it comes to it, we can always try fixing the SNR/line attributes.

--
|Bob Pullen Broadband Solutions for
|Support Home & Business @
|Plusnet Plc. www.plus.net
+--------------- twitter.com/plusnet ----------------
  #5  
Old February 20th 15, 11:41 AM posted to uk.telecom.broadband
Martin Brown
external usenet poster
 
Posts: 343
Default Sudden speed increase but poor reliability

On 19/02/2015 12:32, Alex Fraser wrote:
Hi,

Recently, my ADSL connection (Plusnet) has become very problematic, but
the symptoms seem unusual, and I wonder whether anyone else has
experienced similar and/or can suggest a cause.

Before problems started, downstream was around 6-7 Mbit/s with 3dB noise
margin. Interleaving is on, with some uncorrectable errors but not
enough to be noticeable.


Odd that your line settles to 3dB noise margin. I though the target was
6dB and on difficult lines steps up in 3 (mine has been up to 15dB!).

Increased noise margin gives a falling speed around 500k per dB as a
rough heuristic and vice versa.

I was aware of problems on Friday morning, which I subsequently
established coincided with the end of scheduled maintenance in my area.
Later investigation showed downstream was now 8.5-9 Mbit/s, but with
about 0dB margin(!). And as you might expect, many uncorrectable errors
and (sometimes lengthy) disconnections - an unusable connection, more
often than not.


My noisy line (not Plusnet) sometimes crashes the router overnight and I
end up with a near zero noise margin and a sync light that remains on
even though there is no routing or any IP address shown in advanced
diagnostics. The external health lights on the modem claim all OK.

On Saturday, after plugging the router directly into the test socket and
finding no difference after a few hours, I raised the matter with
Plusnet who did a "broadband reset" (not sure if this is their term or a
general one, but it sounds like the same "calibration" as happens when a
line is first activated; they said "may take up to ten days"): problem
almost instantly solved. I checked at various times and downstream was
in fact somewhat faster (around 7.5 Mbit/s) with noise margin varying
between 3dB and 6dB (part of the process Plusnet had initiated?),
settling on 3dB.


Depending on how much continental MW interference you get you may be
able to game the exact SNR by either syncing just after midday to get
the fastest speed or in the late evening to get the higher noise margin
and therefore a bit more stability. You can see a diurnal variation in
the SNR especially if you run routerstats lite for a while.

I started a thread about it here a while back when I was experiencing
dry joint/cable fracture noise problems on my rural line.

Great, I thought... until yesterday (Wednesday), when the behaviour that
had started on Friday returned.

Has anyone come across similar? Any thoughts as to what is going on?

Thanks for reading,
Alex



--
Regards,
Martin Brown
  #6  
Old February 20th 15, 05:59 PM posted to uk.telecom.broadband
Alex Fraser
external usenet poster
 
Posts: 553
Default Sudden speed increase but poor reliability

On 20/02/2015 10:47, Plusnet Support Team wrote:
[snip]
It's relatively trivial for me to submit another SNR reset (I'd just
need some method of identifying your account). It is fairly odd that
things seem to be going south over time rather than north though.

If it comes to it, we can always try fixing the SNR/line attributes.


Question 99568466 relates to the modify order failing - though when I
queried it I was advised it did go through a couple of hours later. This
remains a mystery as it does not seem to be in effect, but is no longer
desirable (see below) so not worth further action beyond curiousity value...

Despite reasons to suspect changes at the far end causing the issue, and
having no reason to suspect my router, given Graham's comment (thanks
Graham) I arranged to test both ways with another router and connection
(to the same exchange). It was a completely different router: mine is a
D-Link, the other a Netgear.

In short, I found that my router behaved poorly on both connections, but
particularly on my line, while the other router was consistent.

Here are the stats, as a table (NM = noise margin (downstream), dB; DS =
downstream sync, Mbit/s; US = upstream sync, Mbit/s):

My connection Other connection
NM DS US NM DS US
My router 0.0 8.7 0.44 1.0 18 1.0
Other router 3.0 8.7 0.44 3.0 20 1.2

Both routers reported the same attenuation (45dB and 20dB respectively)
for my and the other line.

Based on this alone, it obviously looks like my router is broken (though
the other facts give some doubt that this is the full story). Given
this, and being keen to get a reliable connection, I bought a new
router, which I am now using. It seems to be working OK and behaving
similar to the Netgear router (currently 3.1dB margin, 8.3Mbit/s
downstream).

Alex
  #7  
Old February 23rd 15, 12:09 PM posted to uk.telecom.broadband
PlusNet Support Team
external usenet poster
 
Posts: 995
Default Sudden speed increase but poor reliability

On 20/02/2015 17:59, Alex Fraser wrote:
Question 99568466 relates to the modify order failing - though when I
queried it I was advised it did go through a couple of hours later. This
remains a mystery as it does not seem to be in effect, but is no longer
desirable (see below) so not worth further action beyond curiousity
value...


Thanks for the detail Alex.

You're right, doesn't look like the attempt to fix the SNR worked.

I notice that interleaving has been applied to your circuit though so
I've placed an order to have it removed as per your ticket request.

--
|Bob Pullen Broadband Solutions for
|Support Home & Business @
|Plusnet Plc. www.plus.net
+--------------- twitter.com/plusnet ----------------
  #8  
Old February 24th 15, 08:34 PM posted to uk.telecom.broadband
Alex Fraser
external usenet poster
 
Posts: 553
Default Sudden speed increase but poor reliability

On 23/02/2015 12:09, Plusnet Support Team wrote:
On 20/02/2015 17:59, Alex Fraser wrote:
Question 99568466 relates to the modify order failing - though when I
queried it I was advised it did go through a couple of hours later. This
remains a mystery as it does not seem to be in effect, but is no longer
desirable (see below) so not worth further action beyond curiousity
value...


Thanks for the detail Alex.

You're right, doesn't look like the attempt to fix the SNR worked.

I notice that interleaving has been applied to your circuit though so
I've placed an order to have it removed as per your ticket request.


Based on what my router was telling me ("Channel: FAST" but non-zero
"RSCorr"/"RSUnCorr" counts - and equivalent with the old D-Link router),
I had FEC but not interleaving. Yes, I know that's not normal.

Anyway: no interleaving or FEC now, 1.1Mbit/s up, and the connection
seems basically stable, although the router reports downstream CRC
errors at a rate of around one per minute - I'm not sure at what point
this is worth addressing by increasing target SNR (no obvious problem,
ie packet loss, though, so I guess the answer is "a higher rate than that").

Thanks for your help,
Alex
 




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