Steady line speed suddenly dropped by 50%??

Hi,

We have a long line and slow but steady speed (around 2meg) for the last 4 or 5 years. Over the weekend, the modem lost sync and would only re-sync at well under 1 meg. Not good at all as we rely on the line for business.

I'm a bit off the pace as far as ADSL is concerned but I suspect this may be something to do with BRAS profile which now looks stuck. Is there anything we can do to force the line to re-train please? We've tried rebooting the router a fair few times but no joy.

We are due FTTC in March but we need a steady connection until then as we run a design business from home.

Any guidance (simple speak please!) appreciated. For info we have checked all the wiring, spitter and even a spare modem - same result.

Thanks for your help,
Dave

Could be RFI noise on the line. Can you post router stats - sync speed, SNRM, Attenuation?
Have you recently installed anything new - sky box, phone, microwave etc?
What does speedtester.bt.com say about your speeds and profile?

Hi,

This is the limited info from the router (cheap Belkin N150)

Noise Margin 14 11
Output power(dBm) 12 15
Attenuation(dB) 57 31

Getting 800 down, 400 up at the moment.

Speed Tester gives an IP profile of 705, 800 down, 416 up and 625/326 for the test.

Our download has always been 2.5 x these figures?? We haven't installed any new kit so the problem must be external?

Is this a BRAS issue do you think? Very odd and inconvenient!!

Thanks
Dave

Are those stats taken from the test socket inside the master?

BRAS is the IP profile, the modem is connecting slower than one would expect, 3Meg should be possible.

Has it been unstable? And how long after switching on the modem were those figures taken?

In reply to a post by spon:

We've tried rebooting the router a fair few times but no joy.

Bit late now I'm afraid, but that could have made things worse, by jacking up the sync-time noise margin. We would need the stats taken immediately after a reconnection to know what it is now set at, but the "system's" way of correcting it is Case 4 on this page.

It is possible however that you could get your ISP to do an SNRM reset. They now have this facility but some ISPs don't seem keen on it. Let's see the stats first, straight after a day-time reconnection, preferably using the test socket as mentioned by BatBoy.

Hi Folks and thanks for your help.

The stats are still similar this morning. They are from the normal socket altho we have tried a complete new extension cable up to the router to eliminate that. So all the wiring/splitter has been tried and we've tried a new router but no joy. We have a steady connection - just less than half speed!

Some of the on-line references suggest that it may fix itself in 10 - 12 days? Is this correct please as we can soldier on slowly if necessary. In this period, is it best to avoid any re-boots of the router? I say this as it has an "auto heal" setting where it re-boots once per week in the middle of the night.

Thanks for your help
Dave

The stats don't usually change dramatically over time during a connection, except the noise margin will vary by a few dB. To give you the best advice we need to see stats taken in the same way as before, but immediately after a reconnection.

Re your auto-night-time reboot of the router, that should be unnecessary, and is highly likely to cost several hundred kbps compared to a daytime reconnection. Why do you feel a daily night-time reboot is a good idea?

Please can you describe your cabling. Is it:-

Computer >> short ethernet cable >> router >> ADSL cable >> splitter >> phone extension cable >> phone socket; or

Computer >> long ethernet cable >> router >> ADSL cable >> splitter >> phone socket.

I ask because some people would call a long ethernet cable an extension cable.

Yes, the system is for a high noise margin setting in the DLM to reduce by 3dB every 10-14 days. This can be prevented by a noisy line or one with lots of in-use errors that get dealt with one way or anither without losing the connection, or it can just fail for no known reason.

Hi,

Just rebooted. Stats on router are:

Downstream Upstream
Data rate(Kbps) 896 480
Noise Margin 14 10
Output power(dBm) 0 16
Attenuation(dB) 57 31

Stats on BT tester are:

Download speedachieved during the test was - 694 Kbps
For your connection, the acceptable range of speeds is 400-1000 Kbps.
Additional Information:
Your DSL Connection Rate :896 Kbps(DOWN-STREAM), 480 Kbps(UP-STREAM)
IP Profile for your line is - 790 Kbps

Upload speed achieved during the test was - 352 Kbps
Additional Information:
Upstream Rate IP profile on your line is - 480 Kbps

Our config is socket > long telephone extension > splitter > short telephone cable > router > short ethernet cables to 2 x PCs (+ wireless)

The auto re-boot option is just the default in the router.

So a slight improvement (96 kbps) on yesterday but still way down on what we got for years (around 1.8 -> 2megs)

Thanks
Dave

You would 9 times out of 10 get better and more stable results by plugging the filter into the socket directly. The long extension lead will be subject to picking up RF and other nasties and will just hamper your connection more often than not.

It would be a good idea to test the router in the test socket on the master socket and post up your router stats here right afterwards.

See this for more info:- http://www.kitz.co.uk/adsl/socket.htm

Hi,

Well we just received a mail from our ISP saying that we are due to move on to ADSL2+ overnight and that we've just been moved on to 21CN kit!

Well maybe I'm a bit daft but surely that's an upgrade and not a downgrade?? We are waiting for more advice from our ISP but any recommendations on what to do next appreciated please. Do we just wait whilst BT test (break?) things?

Presumably we should expect the outcome to be positive?

Thanks again,
Dave

Moving from ADSL to ADSL2+ can create those issues on a long line. Requesting a move to ADSL2 or ADSL may be of benefit. You may even be able to set it on your router to override the exchange setting and control it yourself.

Based on your downstream I think this has happened already (the switch to 21CN), as the upstream limit on old ADSL is 448 and you are connecting at 480 currently according to data you posted.

The switching around between ADSL2+ and ADSL2 modes is not likely to make much difference, as your attenuation is pretty much above the area where most hardware will try and use ADSL2+ mode.

Willing to bet that some instability has led to your target noise margin rising from the default 6dB to 15dB, which would knock a meg or two off your speed. If the line is very stable, then once you are outside the mythical 10 days of training to get ISP to request a target noise margin reset to 9dB or 6dB

Definitely 21CN! IP Profile = 88.2% of Sync!

Could be this strange thing of a G.DMT profile on an WBC connection though, about to be changed to G.992.5.

As has been said, that long phone extension cable is almost certainly really screwing your connection. You need to find a way of eliminating it.

In particular it could be (a) low grade cable, and (b) almost certainly contains a ring wire which will not be filtered. A ring wire can cost over 2Mbps, though I don't think it will be that dramatic in your case. It is often also the cause of disconnections.

Long ethernet cables from the router to the computers are however fine, with a maximum distance of 100 metres.

In reply to a post by InQ:

It would be a good idea to test the router in the test socket on the master socket and post up your router stats here right afterwards.

See this for more info:- http://www.kitz.co.uk/adsl/socket.htm

I forgot to include my agreement with this in my reply to the OP a moment ago, but better to do so here now, rather than edit it.

Hi,

Just posted in another thread but as of this morning the connection is still very poor and at 1/3 of what we had before. ISP does not seem helpful at the moment.

This is a big problem for us as we run a successful web business from our home office. Now we can't do anything efficiently other than simple page downloads.

Not sure what my options are now - the FTTC cabs are in place at the end of the street but the service date keeps going back. Not good.

Dave

Re

ISP response so far seems to be "unlucky mate".

from your post in the other thread, that seems hard to believe. Which ISP is it, and had you contacted them before about the clear problem discussed prior to last night in this thread?

Hi,

Forgive our frustration but please see a copy of my update to our ISP this morning:

Sorry but please try to understand our frustration.

I can only apply logic in suggesting that a) we haven't changed anything - our internal telephone line runs under the stairs and whilst long, has been stable for years. It is unlikely to have degraded. b) we tried a temporary telephone connection i.e. a new roll-up version and got the same result. c) we changed the splitter - same result d) we purchased a new modem - same result.

Thus it seems highly likely that the work BT did at the exchange to "upgrade" to 21CN over the weekend caused our problem? Stuck BRAS profile or whatever?

Not quite sure what else we can try and it does seem a bit unfair to start re-wiring the system that has been stable for years? We've also tried to cover all of the main elements with alternatives and get the same degraded result.

Maybe its a long shot but years back, Pipex put pressure on BT when they tried to pull our connection. This was in the very early days of ADSL. BT reacted positively and did "something" at the exchange which gave us a decent, stable connection. Given the recent change at the exchange, isn't it possible that they "undid" whatever they put right all those years back?

Its pretty clear that we haven't changed anything and we've even tried alternatives to all of our cables and kit. Its even clearer that BT have changed something so surely it must be possible for you to ask them what they did and how it can be rectified?? I agree that if some BT chap turns up and tests then he may well not find anything but given the circumstances, this would be way too superficial and needs a more detailed inspection of what has actually happened. Once that's done and we've got our old service back, then I'll consider re-wiring my house if I think there is need to improve the situation. Up until then, putting the onus on us seems a little unfair?

Thanks for your help,

The slow speeds are because 21CN kit has given you a high target noise margin, nothing complicated, just needs provider to request a lowering of it to give you back some speed.

The target of 15dB you appear to have gives stability, but at the expense of a couple of megs of speed.

Hi,

Thanks for that - I agree and I've put it to our ISP to take forward. Although the info given here was informative and very welcome, I was sensing that there was a slightly premature push to start re-wiring everything when all of our tests etc point at the issue being on BT's side. At the moment this still seems to be the case.

Fingers crossed they sort it soon. Toes crossed that they deliver the promised FTTC without any more postponements

Thanks