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Gradual deterioration in sync rate

maranello
Aspiring Pro
Posts: 939
Thanks: 75
Fixes: 1
Registered: 11-01-2008

Gradual deterioration in sync rate

Over the past month I have noticed a reduction in line rate for my connection. After connection/stability problems last year were resolved, I was able to get a stable connection at between 1800-2100kbps, sometimes remaining connected for two months or more, at a target noise margin of 6dB. This is probably good perfomance from a line with 63dB attenuation.
However, over the past month the line has failed randomly more often, and I have been unable to get a line rate of better than 1Mbps, even though the target noise margin still appears to be 6dB. Last Saturday night the connection dropped and resynced at 512 Mbps, which is below the FTR (576kbps) for my line. I managed to coax it back to 768kbps yesterday
I have been monitoring noise margin manually, and even at sync rates up to 864 kbps the noise margin throughout daylight hours has never risen above 7dB. It seems that whilst the noise margin fluctuations are still relatively low, the stable level of noise has increased such that I cannot achieve the sync rates I could previously. Nothing has been changed internally on my phone line, no new equipment added. So I'm working on the assumption that either my router or filters have deteriorated, or something has changed on my line externally.
My next step will be to try to eliminate any internal cause by trying to improve the line rate by plugging directly into the test socket. I'll need to use a plug-in filter as I have a filtered faceplate (fitted by Openreach engineer last September). If I try all the filters I have available and don't see any improvement, I would feel justified in claiming that the fault is either my router or external. If I don't see any frequent disconnections and my line syncs above the FTR, would I be right in guessing that BTw would not view this as a fault even though I had been getting better than twice the speed of recent performance?
Of course, if connecting into the test socket gives me back the line rates I once had, I'll need to look at my equipment. Anyone any advice/experience on how long a router (D-link DSL-2640B) should last when used 24/7?
My other car isn't a Ferrari
8 REPLIES
maranello
Aspiring Pro
Posts: 939
Thanks: 75
Fixes: 1
Registered: 11-01-2008

Re: Gradual deterioration in sync rate

Now getting strange performance. Another random resync occured last night at ~9pm, at 384kbps, just when I was hoping my IP profile would increase from 350 to 500kbps. Fully expecting my PN profile to drop sometime today to 250kbps, I now notice it has increased to 500.  I have on one occasion previously seen the bt speedtester report a profile higher than the sync speed, but dismissed this as just another bug in the tester. Is any of this consistent with Plusnet connection logs?
My other car isn't a Ferrari
maranello
Aspiring Pro
Posts: 939
Thanks: 75
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Registered: 11-01-2008

Re: Gradual deterioration in sync rate


This appears to be a somewhat one-sided discussion, but I will continue anyway just for the record.
Using replacement filters and plugging directly into the test socket with no other telephony devices connected appeared to make no discernible difference to my line rate. So I would guess the problem is either the router or the external line.
The router is less than one year old, but has been running more or less continuously 24/7 for the past 10 months, apart from when I have been away from home on holiday when it was powered down. It's probably worthwhile trying out a different router when I get the chance.
I strongly suspect the line has deterioriated. It may be a coincidence, but the following is an extract from the BT availability checker
Quote
Your exchange is ADSL enabled, and our initial test on your line indicates that it is VERY UNLIKELY you will be able to receive fixed 512Kbps or 256Kbps broadband service due to the very long length of your telephone line. However, your order will be accepted if you still wish to order. An engineer may need to visit who will, where possible, supply the broadband service.

Our initial test on your line indicates that your line may not support a reliable ADSL Max broadband service, with current technology. However, an order for 250Kbps broadband speed will still be accepted, but an engineer may need to visit who will, where possible, supply the service.

This is clearly at odds with my experience, since I have had long periods of stable connection at 2Mbps until recently. Is this a case of BTw being aware of a problem and lowering expectations in the event I raise a fault, or am I just being cynical?

My other car isn't a Ferrari
maranello
Aspiring Pro
Posts: 939
Thanks: 75
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Registered: 11-01-2008

Re: Gradual deterioration in sync rate

Update
Successfully ran a BT Speedtest yesterday evening. I say successfully, it reported the sync rate and my profile (250k), and then reported that the test was inconclusive and advised me to try the next step (which I didn't get around to trying).
Now my profile on both BT and Plusnet systems has risen to 500k. A manual reboot this morning has increased the line rate to 864kbps, so I should get 750k profile if I can keep this going for the next three days.
I never thought that I would consider it an achievement to get a line rate of half what my line was capable of.
My other car isn't a Ferrari
James
Grafter
Posts: 21,036
Registered: 04-04-2007

Re: Gradual deterioration in sync rate

Hi Maranello,
I've just looked at your line and can see that your synchronisation speed is beneath that of the fault threshold rate.
Could you please try a different router and if this does not improve your sync speeds, please raise a fault which we will pass onto BT.
maranello
Aspiring Pro
Posts: 939
Thanks: 75
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Registered: 11-01-2008

Re: Gradual deterioration in sync rate


Thanks James for looking into this. A router change was to be my next step, this coming weekend.
What is my FTR? I thought from earlier problems it was 576kbps, has my router resync'ed since 6:30 this morning?
My other car isn't a Ferrari
James
Grafter
Posts: 21,036
Registered: 04-04-2007

Re: Gradual deterioration in sync rate

Your FTR is 921.
Sync is 832/96 which looks very very bad.
maranello
Aspiring Pro
Posts: 939
Thanks: 75
Fixes: 1
Registered: 11-01-2008

Re: Gradual deterioration in sync rate

Thanks for the info. Confirms a definite resync since this morning. I've never noticed any issues with the upstream rate before now.
My other car isn't a Ferrari
Community Veteran
Posts: 19,099
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Registered: 31-08-2007

Re: Gradual deterioration in sync rate

Upstream sync speed issues, if it's not the modem/router try another filter in the test socket just in case, otherwise it'll be line card unless you have inordinate noise on the line which would make a telephone conversation impossible.