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[JamesK]

Hi All,
I've just come back from a 2 week holiday. While I was away I powered off the modem and router. Since powering up the modem and router on Saturday my connection speed has dropped from around 28-9mbps to 24-25mbps.

The BT availability checker has always said I should be able to get 31mbps. I would say that I'm about 950m from the cabinet. When Infinity was installed the BT engineer disabled all of the phone sockets in the house except the one used for the FTTC connection, as the socket I'm using seems to be wired separately to all the others. The modem is wall mounted and plugged directly into the socket next to it. The router (Asus RT-N66U) is about 8m away from the modem.

To try and find out more I've unlocked the modem and started logging the results continually. I've attached the first batch. The gaps in the reports are where the laptop I'm using to log results needed to reboot for windows updates, etc.

From the limited research I've done so far I've worked out the DSLAM is ECI, Interleaving is on, and I've got a fairly quiet line. Am I right in thinking that DLM has taken some action and reduced the line speed to 25mbps and enabled interleaving? I was under the impression that turning off modem & router while on holiday wouldn't have a negative impact on the line speed. Should this be something that corrects itself in the next few days provided the modem isn't power cycled?

Would really appreciate if people more knowledgeable than me on this could take a look at the output and tell me if the stats look ok, if there's an issue that needs to be looked at and generally explaining the stats to me!

Many Thanks in advance....

[JamesK]

Additional Stats attached...

[waltergmw]

Hi James and welcome,

Just to say we're not ignoring you and that it looks suspiciously like your line has been capped at 25 mbps.
With an attainable rate of over 37 Mbps it seems you should do better but there's not a great deal of spare noise margin.
Let's wait for the real experts to have their tea !

Kind regards,
Walter

[JamesK]

Hi Walter,
Thanks for the update and the welcome  . I didn't think you were ignoring me, as I know pretty much everyone contributes to forums in their spare time... if they have any!

While I was away on holiday I received a text saying the following "dear customers. There has been a BT line fault, we will be back on tomorrow, we apologise for any Inconvenience". I didn't pay too much attention as I was away and the modem/router were all switched off. I did think the wording of the message was a little strange & expected an e-mail as well.  However, it came from a mobile number starting +44 7538 629XXX. So I thought this was perhaps the mobile of a BT engineer attending the incident.

I too, felt that my line speed had been capped at 25mbps. But I wasn't sure if it was as a result of the fault and/or the modem being switched off.

Would it be worth power cycling the modem at this point? Or will DLM resync the modem automatically if it decides to make a change? Apart from powering the modem back up on Saturday morning the only downtime on the modem has been to unlock it in order to start getting the statistics from it.

I've attached 3 days of stats that have been collected and also the current stats for this evening.

Hope this helps... Cheers... James

[kitz]

Hi James and welcome.


I very briefly wondered about capping, but I dont think so because the SNRm sits at around 6dB.   
The bitloading in one of those graphs doesnt look too good in the 100-500 range which to me implies that there is something generating noise on those frequencies.  With those bins not being fully loaded, it will have an impact on the sync speed...   but then that doesnt explain why the router is reporting an attainable rate of 36212....  and now weve gone full circle


Looking at those stats...  if it was an adsl2+ connection and looking at a DMTtool graph, i'd say it typically looks like the modem needs a reboot and resync, because its recovered from a bad sync.

It would be interesting to see the bit loading too at a fresh modem boot to see if those tones are still poorly loaded.


...  and then as Im typing this, I notice your real SNR and the QLN data...  and Im back to wondering what the heck is going on at tones 100-500... 

[JamesK]

I've spent a lot of time this past few days looking through the forum posts and I did notice that my graphs of the bitloading for tones 100-500 looked strange compared to others.

There was a power brick for a Polycom conference phone fairly near the modem until earlier today. I thought it might be a cause of interference, as it's quite large. Is there anything in the house I could look out for which would be generating noise in the 100-500 tone area that could cause it? Or is it likely to be external to the house?

The service has been active for over a year now. For the first couple of months I had close to 30mbps. It then dropped down to around 24mbps for several weeks before slowly getting back up to around 28-29mbps.

The BT engineer who installed Infinity thought that it was odd the socket in the room I've got the modem (top floor of a 3 storey house) was wired to the grey box at the front of the house separately to all the other sockets, and there's lot of them! He said this was good as he could easily disconnect all the others.

I'll do a modem power off/on in a little while. I didn't want to do it in case it would make speed worse. I'll post new line stats shortly.

Cheers... James

[JamesK]

Powered off router and modem, and then all back on again. Attached are the updated current stats. I'm not seeing any difference. Would it be worth calling BT and asking for clarification on the fault I received a text message about?

[Bald_Eagle1]

Your DS sync speed does indeed appear to have been capped/banded.

Any sync speed ending with 998, 999 or 00 confirms it has been banded.

Your US sync speed is not banded, as confirmed by the variable sync speeds & Interleaving depth of 1.


Along with the comments regarding your QLN & SNR graphs, your quite high DS Interleaving depth of 1771 also confirms your connection is/has been 'noisy' or it has recorded high error counts.

Lower down the Plink log, you will see data against INP & delay.

The lowest level of INP (Impulse Noise Protection) is usually 3.00 DS & o.oo US.
The lowest level of delay is usually 8.00 DS & 0.00 US.

DLM may attempt to increase sync speed & lower interleaving/delay levels if a few days of stability/low error counts are recorded, but isn't unknown for DLM to 'stick' for many days at a time, sometimes apparently indefinitely.

Finally, DS Bitswapping seems quite high(ish), suggesting that bitloading can be a little sporadic. i.e. sometimes some tones are unavailable, so bitloading is swapped around.

A 'quiet' connection would typically report around 12 bitswaps per minute during the daytime, increasing to around 20 or so overnight.

[JamesK]

Would it be worth me trying to raise a case with BT regarding this? I'm concerned whatever the fault was that I received a text about while on holiday could be the cause of any errors/noise on the line. Up until going on holiday the speeds had been stable for 10 months.

[waltergmw]

Hi again James,

IMHO you will need a VERY STRONG determination if you are to attempt a resolution through BT India.
I suggest you try all you can yourself to investigate noise sources including all the old favourites such as faulty fluorescents, street lights, boiler thermostats etc. etc. etc.

When you are ready to talk to BT, prepare all the evidence from the wonderful Bald Eagle's facilities together with a brief history of what you have attempted.
Put all this in a PDF document and then "on-line chat" to India downloading the PDF immediately.
Cut & paste the chat as it proceeds into a separate document.
Record and add any other names / and engineers involved at all times.
If Openreach contact you by mobile record the phone number if available.
You may well have to jump through all the usual hoops of power-resetting modem, using the test socket with a filter etc. etc. but as soon as you can say you want your PDF reviewed by a level two desk person.
DON'T be fobbed off with having to wait 24 hours for the level two to ring you back.
IF and when you get to the stage of arranging an appointment insist it is a morning one and say you want a VDSL specialist.
You probably won't succeed the first time but patience is a virtue.

If you are offered to take a survey ensure it is full and frank & include your e-mail address.
One day BT may just wake up to the fact that VDSL maintenance requires very substantial and well trained resources.

You may well find that the BT subsidiary PlusNet (or any of the better smaller ISPs) handle things more easily for you.
Most waste less of your time with delays and obfuscation but all rely on the splendid experience of dedicated Openreach technicians such as our excellent BlackSheep.

The very best of good luck !

Kind regards,
Walter

[JamesK]

Many Thanks for the advice on ways I need to deal with BT India. I've also dropped a message onto the BT Community Forum as I know the mods there can sometimes fast-track stuff if they see it as an issue.

There's not a lot in the house that has changed in the last few weeks that could've caused an increase in noise. I know I can't rule out something starting to go wrong, such as the thermostat on the boiler. The house itself is only just over 10 years old.

I've taken the BT socket off the wall, and all looks good with the wiring there (only 2 green wires connected). I've also replaced the RJ11 lead for a decent CAT6 one from e-Bay of the shortest length I could get to see if that helps as well.

In the meantime I'll keep logging the connection statistics.

However, I still think that whatever fault occurred while I was on holiday has something to do with the loss of speed I'm now experiencing. As well as being on a higher speed before I went away, the ping rate was also always a lot lower whenever I did a test on speedtest.net, which would tie up with interleaving now being on as well.

Best Regards... James

[burakkucat]

I've taken the BT socket off the wall, and all looks good with the wiring there (only 2 green wires connected).

   If possible a picture or two, attached to a post to this thread or made accessible to view elsewhere, will allow us to examine what you have seen.

The socket to which you refer is an NTE5/A?    (Example image at the top of the page.)

[JamesK]

This is the socket... I didn't take any pictures inside it though...

[burakkucat]

Thank you. So that confirms an NTE5/A plus SSFP combination is present.

I think we can therefore rule out any problems in that area.

[waltergmw]

@ James,

Although the green pair indicates (Normally it's the blue pair) that the NTE5 is not directly connected to the drop wire, but that in itself doesn't usually cause a difficulty.
If you can get to the junction box where the drop wire is terminated it would be worth checking the crimps and removing the cobwebs.
HOWEVER if you do touch the wires be very careful not to snap any corroded ones, unless you have found some crimps from somewhere.

Kind regards,
Walter