Improving Noise Margin & a Possible Bridge Tap

Hello.

I've been connected to a FTTC service (Plusnet) for over 3 years now, speeds generally great at around 23-28Mbit (has been improving over the years!) - this is great as I live around 1.5km from my cabinet. Estimated speeds on a clean line at between 13-21Mbit.

I am currently and have always been plugged in to the master socket (test socket with micro filter at the moment) with a faceplate filter

I recently logged an issue where my router displayed connection speed became 'stuck' at 19999kbps and thought this was unusual as it had never been so low (this figure did actually improve to 22400kbps on the morning just before the engineer visit).

A fault was found and a (non-broadband) Openreach engineer 'fixed' the issue with the line (apparently no dial tone - we never use the land line so were not aware). Unfortunately this fix has made our connection speed even lower (ranges between 13-18Mbit - it has never been this low before!) and more unreliable where the connection appears to drop more often especially in the evenings.

I have told Plusnet but they give the 'It's within expected range' response which is unhelpful considering the connection has been great for the past 3 years!

Interestingly, since this fix, I now notice dslchecker has changed the 'Bridge Tap' part from N to Y which could explain the issues.

Before requesting a further investigation from Openreach and possible incurring a call out charge I have done some investigation to ensure there's no dodgy wiring. We only have one extension which will be removed as this is never used. I have also taken a look at the back of the master socket (Openreach side) to ensure everything is correct, which it is. So ultimately, there's been no changes to our wiring since we've had FTTC.

I have however noticed that this appears to be a very old master socket type, probably 80's. I also noticed that when I touch the area illustrated in this image the Noise Margin will improve by 1-2db (ie, go from 6.2db to 8.1db) - is this normal or does it show the socket is faulty?:

http://joxi.net/Grq7KDXUQd8G82

At the moment I'm a bit perplexed on what to do next. I am beginning to wish I never reported an issue!! Ha!

I currently use a Netgear D6400 router, as I understand it this doesn't give out much in the way of useful stats.

Any thoughts or advice?

Thanks
James

When you say there is an extension which you will remove, is that extension connected to the faceplate of the master socket, or is it connected to a junction box somewhere between the extension socket and the point at which the incoming line reaches the house?

If is is connected to a junction box that is feeding it and the master socket then that is where you need to disconnect the extension by removing its wires. That is the bridge tap point.

Removing the extension socket itself while that connection is present would make no difference. Cutting the wires at the junction box I expect would help but is not the correct solution.

If that Terminal B isn�t properly connected then it obviously needs to be. Is there insulation trapped in it?

Edited by RobertoS (Tue 09-Oct-18 09:30:15)

Thanks Roberto.

The extension runs from the back of the master socket faceplate, so as I'm using the 'test socket' at the moment this extension is not live.

As far as I'm aware, and can see, the phone line enters the house and terminates at the master socket only. There's no other sockets.

Regarding terminal B, I'm sure everything was correct but I'd have to take a closer look tonight.

If there was no dial tone at the test socket previously and no new socket fitted suggests one leg was previously disconnected, and now you mention possible lose screw b, so maybe that has been the problem all along.

NOTE: DSL will work with only 1 wire from a pair connected but a phone will not, thus checking for dial tone is a good test to do.

The age of the master socket should not really matter i.e. nothing too magical about the new ones.

Touching the "B" terminal could also act to provide a path to earth for some of the noise.

I did wonder about that. Possibly wrongly I didn't think for long enough to get anywhere with it.

I checked both terminals last night, nothing incorrect from what I could see, both terminals tight, no insulation trapped.

Just to rule out any issues with the master socket and any internal wiring, I swapped this with a new one (NTE5c with faceplate) while also removing the unused extension wiring (We don't use the land line, so removed them all!). At this stage I can't really see any improvement and my speeds are no better, I also had a couple of disconnects overnight and I rebooted this morning.

Current stats show:
http://joxi.net/v29BDzPU3lPz9A

The downstream noise margin was around 6.5db after rebooting about 8am). It will stay high throughout the day then drop away around 6pm, to around 4db during the evening where it may resync if the db drops low enough.

What is annoying is that up until the engineer fixed a 'fault' I wouldn't drop a connection in days/weeks. Now it appears to be at least 3-4 times a day. I believe it's likely that the recent 'bridge tap' on the line is probably causing the issue - DSLChecker: http://joxi.net/12M94nYhMbo8B2

I guess my next steps are to find a corded phone and try a quiet line test, then logging a fault with Plusnet again.

Cheers
James

Edited by slimj (Wed 10-Oct-18 09:44:43)

From your previous description I suspect the bridge tap diagnosis is spurious.

In reply to a post by MrSaffron:

NOTE: DSL will work with only 1 wire from a pair connected but a phone will not, thus checking for dial tone is a good test to do.

Yes, but it will only work at a much slower rate.

Is anyone else getting a trojan alert when trying to access the screenshots? I'm using the amazing Malwarebytes. ;P

Edited by deleted (Thu 11-Oct-18 16:40:39)

Is anyone else getting a trojan alert when trying to access the screenshots?

No, are you meant to?

Yes MBAM is blocking outward connections for me with a Trojan warning.

Just to update this.

Openreach engineers visited today as I wasn't satisfied with the resolution (speeds seem to have got stuck at 13mbit!). Discussed everything with them and they checked the line, they found an unacceptable amount of errors, they have determined it may be related to a large tree rubbing on and stretching the dropwire to my property. They also noticed the cover on the box at the top of the post (not sure what this is) where the cables connect to had broken off so could also be a factor as it's exposed to the elements.

I advised about the Bridge Tap and they believe the tree and missing cover could attribute to my issues.

Openreach are coming to fix these issues on Friday morning. Fingers crossed they just run fibre all the way to my property...

Hmmm, OH and trees is never a good combo .... but it whilst it might give you an HR fault, it won�t give you a bridge tap ...

Good luck, keep us posted.

Some good news.

The line was replaced this morning and some of the connectors were also discovered to be faulty (where the dropwire reaches the house).

They ran their usual suite of checks and the line had a max connection speed of 27mbit on his hand held device. However, due to a number of CRC and FEC errors he could only get a max speed of around 22mbit (typical of the speed I have seen for the past 3 years) - he was seeing these errors before the line was replaced.

So while the replacement line has solved an issue, they believe that there could be some electrical interference in the area (REIN) causing the errors as a neighbour was also having a similar issue. Mine and my neighbours faults will now be combined and a REIN engineer should be in touch.

Noise margin tends to be ok from 8am to 6pm, then will drop after this. So I guess it's a matter of finding the source of this interference - My initial thought was street lights but there's nothing in close proximity to the lines from what I can see (only 1 on the main road near where the phone line comes out the ground).

Saga sort of continues

Good luck getting a REIN engineer out after 6pm.

Did the errors continue after the line was replaced ?

This has clearly been done during the period you say isn�t an issue, and yet there were errors then, so I suspect that REIN diagnosis is a red herring.

By surprise, after another Openreach engineer turned up at 8.30 on Saturday morning to run a few more tests (he also changed some things in the cabinet). CRC errors seem to have gone too. It definitely feels like things have have notably improved since the line was replaced which is great news!

Router stats are currently showing...
Connection Speed: 23554 kbps / 1109 kbps
Line Attenuation: D0( 26.7) D1( 67.0) / U0( 13.2) U1( 71.5)
Noise Margin: 10.4 / 6.2

Unfortunately my Netgear D6400 doesn't give max attainable or any further stats. But I definitely feel this could improve further over the coming weeks.

The only thing I have noticed is that speed tests seem to top out around 14mbit. Indeed, downloading a 3gb update on Xbox last night I seemed to be hitting this as a maximum speed.

Would I need to get Plusnet to check to ensure there my profile is not stuck? It was stuck at this speed just before I had the drop wire replaced.

Many thanks.

IIRC you can enable telnet on the D6400 by going to the debug page:

http://192.168.0.1/debug.htm (or replace the IP with your router IP if different)

You can then telnet to the router to get further stats. I can't remember on the D6400 if you need to log in (often username gearguy and password geardog).

Platforms like Xbox live and others are not good judges of whether a connection is running well

If the sync is 23554 Kbps on the download then speed tests should be well above 14 Mbps, so time to link to one of those speed test results, you may have ISP TCP/IP issues too

In reply to a post by MrSaffron:

Platforms like Xbox live and others are not good judges of whether a connection is running well

If the sync is 23554 Kbps on the download then speed tests should be well above 14 Mbps, so time to link to one of those speed test results, you may have ISP TCP/IP issues too

Just tried a test with a wired connection. Appears to be the fastest speed I can manage.

Log into your PlusNet member centre and check what they have configured for the current speed of your line looks like the IP Profile mirror system has missed out on a sync speed changes

In reply to a post by MrSaffron:

Log into your PlusNet member centre and check what they have configured for the current speed of your line looks like the IP Profile mirror system has missed out on a sync speed changes

Ah! This is showing 14.1mbit. Personally thought this wasn�t in use any more?!

I�d imagine it�s been stuck there for a week or two as my download speed doesn�t increase with increases in connection speed.

Cheers.

In reply to a post by slimj:

Ah! This is showing 14.1mbit. Personally thought this wasn�t in use any more?!

Definitely still in use. This time mine did increase when my sync speed last increased, showing 73.8Mbps against IP profile of 74.1 Mbps. I thought it was only supposed to be 0.1 Mbps less, but I'm not complaining. You might have a little difficulty getting Plusnet to understand the problem, but they'll get there in the end.

Edited by kasg (Mon 29-Oct-18 18:42:47)

I also ran the BTWholesale speedtest this morning, this showed 13.21Mbps, with a max achievable speed of 22.77Mbps.

I've sent plusnet an email to get this resolved now. But inbetween running the test this morning and emailing plusnet my plusnet account now shows a line speed of 22.6Mb so perhaps this has resolved itself (at work so can't check)?!

Good news, plusnet did a reset on my line speed and my speeds have increased.



My connection speed on my router is gradually improving and is currently showing around 24mbit with an 8-10db noise margin - I'd imagine this will improve further as the noise margin reduces.