Plusnet ADSL+ used to be 4Mbps and now its 2Mbps

Our home laptops have been loosing their wireless connectivity and dropping out. Was quite shocked to learn that the download speed had halved. Had the account for many years now. Could Plusnet be snipping bandwidth to force us onto fibre or is it just an increase in the number of users using copper lines. Still usable at 2Mbps but would like it higher. Thought of replacing the modem for one that allows the SNR to be tweaked. Its currently 9.3dB and the attenuation is 53dB. Any thoughts on this?

Edited by deleted (Mon 27-Jul-15 17:25:23)

If the problem is wireless signal dropping out that then the ADSL is irrelevant, wireless is a different technology and can be affected by many things.

You need to

a) Post the full set of modem stats, connection speed, attenuation and noise margin for download and upload
b) Do some testing using an Ethernet cable to see if that is also demonstrating the slow speeds

Thanks for that. I did a speed check using various checkers and all are reporting the 2Mbps figure. Contacted Plusnet but they said that unless the speed fell below 1.5Mbps they would not class it as a line fault. I knew the line had interleaving set to on so I asked them to turn it off and the SNR value fell from 12 to around 10 which I believe makes things technically worse although haven't noticed any change. The stats I have quoted come my modem routers stats page.

And the actual connection speed (modems don't report at 2 Mbps exactly so I know that's now the figure), seeing the full set of both download and upload is important to help judge what is going on with the speed.

So it is 2 Mbps when also using an Ethernet cable?

Turning off interleaving and reducing the SNR margin may have had the effect of increasing the number of errors and actually slowing you down i.e. it may be taking 2 or 3 packets now to get every single useable packet to you, while with interleaving turned on this more like the desired 1 to 1. Why did you ask for interleave to be turned off?

The speed test results are here:

http://www.thinkbroadband.com/speedtest/results.html...

I was researching an upgrade to a new modem and read about the Billion 8800n having SNR adjustments to achieve highest sync speeds. They way this seems to work unless I've read it wrong is adjusting the SNR downwards improves speed. So taking the interleaving off did lower the SNR with no to improvement in speed. I take your point on packets so if there is a problem I can ask them to turn it back on. Leaving it where it is for the mo.

AFAIK the router you are probably using is giving you a figure for the SNR Margin not the actual SNR, therefore there would appear to be possible issues with your connection when the exchange equipment has raised the noise margin to around 12dB which would also lead to a lower sync rate and throughput.
http://www.kitz.co.uk/adsl/linestats.htm#SNR

If you have a new mastersocket with a TEST socket within it connect the router to the TEST socket and using an ethernet cable connect the PC to it and get the router line stats.

http://www.kitz.co.uk/adsl/frogstats.php

If you can do the BTw Test:- http://speedtest.btwholesale.com/ as well plus the next part of it with the Diagnostic Tab at the bottom of the web page as this Diagnostic test gives extra info.

What info does this give after you have logged in:-

https://portal.plus.net/my.html?action=data_transfer...

Can only infer that the connection speed is somewhere above 2 Mbps from that test result, but other than that no sign of congestion or line errors.

So if the modem really is reporting a sync speed of say 2176 Kbps then it is possible you might double the speed by turning interleave back on, this is because things are not totally predictable as noise is a funny beast.

The Billion 8800 might let you set the SNR margin lower, but that might increase errors and cause more disconnections or see slower speeds

Without seeing the connection data that I've suggested hard to be slightly more confident

In reply to a post by Apprentice:

AFAIK the router you are probably using is giving you a figure for the SNR Margin not the actual SNR, therefore there would appear to be possible issues with your connection when the exchange equipment has raised the noise margin to around 12dB which would also lead to a lower sync rate and throughput.

I'd looked at Kitz but my combined modem router does not support command line instructions so its not on their list of compatibles. As for the master socket not sure whether its an NTE5 or an ADSL Service Specific Faceplate (SSFP). As the house slave sockets don't require external filters it suggests the latter. As I remember there is a high spec twisted pair cable wired to an internal RJ11 running for about 3 metres to the modem RJ11. Its a bit of a hassle getting to the SSFP and using the test socket so that's a no go for the moment. The router stats do specifically refer to 'SNR Margin'.

I Did the BT Wholesale test as Plusnet recommend and it came back with the same speed of about 2Mbps.

Logging in to the portal as you suggested it says the speed it currently 2.1 Mbps.

The router ADSL stats is reporting a downstream speed of 2.414 Mbps. SNR Margin is 8.9 dB Attenuation 53 dB Output Power 18.3 dBm Superframes is 9294612 with RS Correctable Errors at 10424 and RS Uncorrectable Errors at 3739. HEC Errors is 4108 and Total Cells is 1060288 with Data Cells at 6967917 and Bit Errors at 0.

Upstream: 414kbps. SNR Margin is 13.3 dB Attenuation 30.6 dB Output Power 11.3 dBm Superframes is 9312559 with RS Correctable Errors at 928 and RS Uncorrectable Errors at 29. HEC Errors is 0 and Total Cells is 937033 with Data Cells at 2903113 and Bit Errors at 0.

The Lan Wireless Stats Received is reporting Bytes 100128732 Packets 1020654 Errors 120626 and Drops 120644. Transmitted Bytes 326530246 Packets 1167855 Errors 903 Drops 903. I think the the wireless errors work out at 1%?

Wan Stats VPI/VCI 0/38 Protocol PPPoA Received: Packets 750042 Errors 0 Drops 0. Transmitted: Bytes 326828328 Packets 244772 with Errors 0 and Drops 0.

I'm fairly sure its not an equipment issue at my end but until the speed drops below 1.5 Mbps BT will not treat this as a fault. ADSL speed is from my perspective undergoing a continuous degradation not related to the modem technology in use.

And WHY did you ask for interleave to be turned off? It seems this was the cause of the lower sync and you may find the sync comes back again.

The connection speed is low for the sync, but likely to be within what Openreach will be happy with.

General rule when changing things, if something is worse after doing a change you reverse the change.

In reply to a post by MrSaffron:

And WHY did you ask for interleave to be turned off? It seems this was the cause of the lower sync and you may find the sync comes back again. The connection speed is low for the sync, but likely to be within what Openreach will be happy with. General rule when changing things, if something is worse after doing a change you reverse the change.

The WHY is an empirical approach to fault finding. By leaving the interleaving off and observing the effect over a period of time determines whether it should be turned back on again. Not enough time has elapsed to reverse the change. What I do know for sure is that when it was switched on the SNR Margin was higher and now its turned off this value is lower but the user experience remains the same and so does the download speed being reported from various sources.

I replaced the modem router with its spare and the download speed was the same. Given that the modem router its settings and wiring to the master socket have not changed they remain a constant experiencing change from an external variable. There seems to be an unidentified mechanism at work that is lowering ADSL download speeds?

Obviously confused, as you seemed to originally suggest that the connection had been running fine at 4 Mbps with interleaving off.

If this is just your 'experiment' will back off from offering further advice as you seem keen to enjoy the learning experience.

In reply to a post by MrSaffron:

Obviously confused, as you seemed to originally suggest that the connection had been running fine at 4 Mbps with interleaving off.

Not Quite! With the interleaving on, the the historical (over ten years) download speed was between 3-4 Mbps. The download measured during that time by online instrumentation was saying the line was capable of 4 Mbps. Its only in the last couple of weeks that we began loosing the internet connection. When the download speed was measured it had surprisingly dropped to between 1.9 and 2.4 Mbps.

Before asking Plusnet to remove the interleaving the download SNR was being reported at around 12 dB after it was removed it dropped to between 9-10 dB. Lets say 9 this is a drop of 3 dB which doubled the noise with little or no apparent change to the download speed. Would have expected it to drop by quite a bit, it didn't.

Back ten years or more I asked Plusnet about fair usage and they said that the bandwidth was shaped but for video download something realising the nature of the download kicked in to increase the speed. Not sure this is true anymore as we are only 500 kbps from the lowest acceptable limit of 1.5 Mbps.

So I'm stuck in limbo with nowhere to go. Need to go around copper/fibre and cabinets and that's proving a real learning curve. I've dismissed satellite because for home users there are no open ports. Looking at 3G/4G modem routers with an external antennae but lack access to a field strength meter and service identifier to see whether this is viable in my location. Thanks to everybody who replied to the original post.

With the reported downstream attenuation etc. the router could be able to sync with the exchange up to say 4Meg on an issue free connection and the SNR margin at around 6dB.

If you want to monitor the SNR margin and connection speed you could try "Router Stats Lite" providing it will work with the router in use.

http://www.vwlowen.co.uk/internet/files.htm#routerst...

If the SNR margin doesn't eventually come down to 6dB via the DSLAM/exchange equipment and Plusnet don't see any errors/problems on your line connection via their equipment I think you can still ask them to reset the SNR margin to the default 6dB, it's up to them though but they used to do it in the past.

In reply to a post by Apprentice:

If you want to monitor the SNR margin and connection speed you could try "Router Stats Lite" providing it will work with the router in use.

Thank you. Very nice instrumentation, installed and working.

If I might share, this article explains the role of SNR Sync.

http://www.increasebroadbandspeed.co.uk/SNR-tweak

A table in the article says with an SNR Target of 12 dB I should be getting around 4 Mbps and with a Target of 6 dB I should get 5.5 Mbps but adds a caveat that increased line drop outs and errors can occur at this value. It also says that the DLM/DSLAM is continually tweaking the SNR Target which with interleaving off now sits at 9 dB (4.7 Mbps).

On the graph I can see very small adjustments to the SNR but the download speed is a flat line of 2.414 Mbps - not a ripple anywhere even when playing a youtube video. The instrumentation is reporting router stats which is not necessarily the same as the exchange SNR Target?

Rather than mess with the good folks at Plusnet I'm thinking of upgrading the modem router to a Billion 8800nl which will give me an upgrade route to fibre should I go there. What I will be able to do is adjust the SNR Target myself to see if speed increases or decreases. I'm aware that this must be done slowly in 1 dB steps on a set and observe basis. But I'm not hopeful because the download speed is way below what it should be. What can I do if Plusnet are deliberately shaping the bandwidth to this lower value?

Yes, it is reporting router stats. So except on re-syncs the speed will be constant.

The movement of the SNRM is what you want to see. I used to set the bottom of the y-axis to about -3dB - some routers can report as low as -1dB without losing connection. A maximum value of 18-20 should be fine at first, then reduce it to something much lower - say not more than 4dB above your 24-hour maximum.

I used to set the sampling interval to the minimum (7 seconds?) and the graph timespan to an hour or so. Some people like it on much coarser settings. It depends what you are wanting to monitor.

Those settings let you see exactly what is going on if your line is unstable. Set the graphs to save, and save on close. I also used to set up a save to log file as it's easy to scan on your screen. Be careful what is saved there though - I don't fully remember what the options are, but on a different similar tool I remember it defaulted to include the SNRM for every tone. Which is rather more detail than we normally need. The single overall figure as reported in the router GUI and on the graph is all you need.