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Steadily Increasing Noise Margin / Decreasing Bandwidth - DLM Reset and/or line test

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Plusnet Help Team
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Registered: ‎24-07-2014

Re: Steadily Increasing Noise Margin / Decreasing Bandwidth - DLM Reset and/or line test

From the form being submitted, it takes around 3 working days, so possibly didn't come off in the early hours.

If this post resolved your issue please click the 'This fixed my problem' button
 Tony T
 Plusnet Help Team
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Re: Steadily Increasing Noise Margin / Decreasing Bandwidth - DLM Reset and/or line test

Hi @arooney

 

Thank you for your update. I have tested your line again today and can see the sync speed was 38.4Mbps.

 

If you could let us know how things are from your side over the next week or so, just to ensure no further actions are required.

 

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 Katie C
 Plusnet Help Team
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Registered: ‎25-02-2020

Re: Steadily Increasing Noise Margin / Decreasing Bandwidth - DLM Reset and/or line test

Hi @KatieC,

Thanks for checking my line.  The download speed has certainly improved since the banding was removed, which is great.  As you say, let's see how things go over the next week or so, and I'll check back in.

Thanks for you help (along with @plusnettony and @RealAleMadrid) so far.

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Plusnet Help Team
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Re: Steadily Increasing Noise Margin / Decreasing Bandwidth - DLM Reset and/or line test

Hi @arooney,

I've tested your line today and I can see it's now syncing at 33.5Mbps down and 8Mbps up. I hope that everything is okay on your end of things, but if you have any further issues or queries that you wish to raise with us then please don't hesitate to get back in touch.

If this post resolved your issue please click the 'This fixed my problem' button
 Alex H
 Plusnet Help Team
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Re: Steadily Increasing Noise Margin / Decreasing Bandwidth - DLM Reset and/or line test

Thanks for the follow up @TheMightyAJ.  Looking at my current router stats I can see the line rate had dropped slightly since the last week, with it now syncing at exactly 35 Mbps:

 

DSL Link Downstream Upstream
Connection Speed 35.00 Mbps 8.09 Mbps
Line Attenuation 26.70 dB 26.30 dB
Noise Margin 6.80 dB 5.10 dB

 

This does lead me to think that DLM has once again started banding the line and reducing the sync rate.  The rate is still decent, I'm just concerned that over the coming weeks, DLM will continue reducing the rate every few days or so.

I have been tracking the line drops, as logged by my router, and these still happen intermittently, sometimes once a day, sometimes less frequently, and always overnight when I'm not using the internet.  E.g.

[Internet connected] IP address: 143.159.81.204, Wednesday, March 18, 2020 02:54:04
[Internet disconnected] Wednesday, March 18, 2020 02:53:20
[Internet connected] IP address: 195.213.36.51, Tuesday, March 17, 2020 03:02:48
[Internet disconnected] Tuesday, March 17, 2020 03:02:10
[Internet connected] IP address: 195.213.36.31, Sunday, March 15, 2020 22:15:45  # Router Restarted!
[Initialized, firmware version: V1.0.1.56] Sunday, March 15, 2020 22:15:29 
[Internet connected] IP address: 195.213.36.31, Saturday, March 14, 2020 02:42:40
[Internet disconnected] Saturday, March 14, 2020 02:42:00
[Internet connected] IP address: 195.213.36.31, Saturday, March 14, 2020 00:58:04
[Internet disconnected] Saturday, March 14, 2020 00:57:25
[Internet connected] IP address: 195.213.35.66, Friday, March 13, 2020 03:05:47
[Internet disconnected] Friday, March 13, 2020 03:05:19
[Internet connected] IP address: 195.213.35.66, Tuesday, March 10, 2020 08:38:26
[Internet disconnected] Tuesday, March 10, 2020 08:37:56
[Internet connected] IP address: 195.213.35.66, Monday, March 09, 2020 01:19:25
[Internet disconnected] Monday, March 09, 2020 01:18:23

I believe the disconnect on March 10th at 08:37:56 was when the DLM banding was removed.

There's no obvious pattern here (from my point of view), and I have no idea what is causing this.  It doesn't interfere with my usage at they are always over night, but I'm concerned that DLM will see these and steadily reduce the line rate.  I don't know what the root cause of these disconnects it, but given that it happens when I'm not actively using the line, leads me to suspect it may be something external to my property, perhaps the DSLAM port back at the cabinet?

One question, are you able to confirm the NGA profile being used for my line?  Is this the "speed" profile (to prioritise speed over line stability)?  If not, can it be set to this?

Regards, Alex R

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Plusnet Help Team
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Re: Steadily Increasing Noise Margin / Decreasing Bandwidth - DLM Reset and/or line test

Hey @arooney,

Thanks for getting back to us.

 

From testing your line today you are currently syncing at 31mbps download, there's no banding currently on the line. I can see the drops in connection are occurring at around 2am each night, do you have any electronics in the house such as a DVR/HIVE setup that may causing these drops?

 

We can of course change the settings on your line to see if it would make any difference in stability (although this would slow the speed down). If this is something you'd like us to do let us know here.

 

Thanks.

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 Maddy S
 Plusnet Help Team


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Re: Steadily Increasing Noise Margin / Decreasing Bandwidth - DLM Reset and/or line test

Hi @Mads,

Thanks for following up.

I've been tracking the line drops from the router logs, but I can't see any pattern to them.  They don't happen at exactly the same time, although they are generally in the 1am to 3am time frame overnight, and they typically happen once every 1 to 2 days, but not every day.

We don't have a HIVE setup in the house, although we have lots of the typical devices connected to the router, including a Sky+ box, DVD player, PCs and laptops etc.  It doesn't seem logical to me that any network end point in the house would be causing the router itself to drop the WAN connection.  Having already replaced the router several months ago to try and resolve these issues, I'm also reasonably sure it's not the router itself.  It seems more likely the problem is external to the property.

From my perspective the line is stable - it never drops during the day when we are actively using the connection, in the small hours when we are not active, so no, I don't want to change the settings to make the line more stable.

My concern here is that the DLM algorithm will continue to reduce the bandwidth as it sees the occasional line drop.  This is what has happened previously, where over a period of months we lost almost 50% of the bandwidth, with absolutely no improvement in the line drops.  If anything, I would like the line settings changed to prioritise speed over stability.  If you can confirm whether or not that's possible, that would be appreciated.

Regards, Alex

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Re: Steadily Increasing Noise Margin / Decreasing Bandwidth - DLM Reset and/or line test

Hi @Mads 

Unfortunately a few more overnight line drops and I'm guessing DLM has further limited my bandwidth, with my router now syncing at just over 27Mbps:

 

DSL Link

Downstream

Upstream

Connection Speed

27.40 Mbps

8.15 Mbps

Line Attenuation

26.70 dB

26.20 dB

Noise Margin

11.30 dB

5.90 dB

 

I'm going to start disconnecting everything from the router overnight to try and rule out anything internal, but it really feels like something external is triggering these line drops.

I'm not sure if you or one of your colleagues would be good enough to check my line profile and confirm whether or not it can be changed to prioritise speed over stability?

Regards, Alex