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Low SNR/connectivity issues

jab1
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Registered: 24-02-2012

Low SNR/connectivity issues

For the past week or so, I have been finding that late evening pages have taken ages to load, or even totally failed. So, last night when this occurred even earlier, I went hunting for a reason, and I think I've found it! Namely horrendous SNR and attenuation  figures on the downstream side - I encountered attenuation at 51.5dB and SNR at 3.46 - and NOTHING, unsurprisingly, would load.
So, this morning, I ran the requested tests, and the results are below. Hope someone can solve it, as losing connection in the middle of doing banking or online shopping is not something I enjoy.
BT speedtest                      4530kbps down  374kbps up
IP profile                              5.11Mbps
Router Stats:
Connection speed                5791kbps down/374kbps up
Attenuation                          50.5dB down/23.5dB up
SNR                                    5.15dB down/17.0dB up

Estimated line speed (checked 31/01/12)  4.0Mbps
All tests conducted wired into the test socket.
John
21 REPLIES
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Re: Low SNR/connectivity issues

The probable reason nothing would load is a very high error rate when the noise margin drops too low.
Basically your sync speed is too high for the attenuation in the evening
To explain
You seem to have a very clean (low noise) line during the day which then goes bad at night and although your router is holding sync the errors are killing your connection.
Have you tried doing a resync in the evening when the noise margin is low and then leaving the router on all the time
The ultimate solution is to ask for the default noise margin to be increased to 9dB (I am not sure that this can be done but it may be worth considering)
For a comparison these are my stats and I thought I was doing well
Noise Margin:    5.5  dB
Connection Rate:  4928  Kbps
Line Attenuation: 50.0  dB
There is, however, another problem. Your upstream sync speed is odd. You state that it is 374kbps with a noise margin of 17dB - are these numbers correct as you should be getting 448kbps or just a bit less if you are on ADSL2+
jab1
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Re: Low SNR/connectivity issues

Thanks for the quick reply, Jim
I understand your explanation - in a former life I was IT support when the term haddened even been thought of  Smiley
Not tried a resync - presumably that is just a disconnect/reconnect? - sorry, but my former life was a long time ago, and my memory isn't what it used to be.
The router is left on 24/7 anyway, unless I am going to be away for an extended time,when everything electrical that CAN be switched off, is.
Upstream figures are correct - and constant., and thinking about it, do seem a little strange. Not thought about it before, but I do quite a few online quizzes, and had noticed my times seem to have increased, which that may explain.
Thanks
John
John
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Re: Low SNR/connectivity issues

You are correct that is is a connect/reconnect but not just the PPP session but also the connection with the exchange
jab1
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Re: Low SNR/connectivity issues

Thanks - so an unplug/replug of  the router?
John
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Re: Low SNR/connectivity issues

That is one way.
I do it via the router web interface
jab1
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Re: Low SNR/connectivity issues

UPDATE
Same problem about 18.30 last night - so I did a resync, which didn't appear to achieve anything. Switched off desktop & laptop and read book instead.
Started up this morning and did the tests again, but NOT through the test socket as it involved a lot of faffing about moving equipment.
Results were much more encouraging - downstream SNR now 6.25dB, but the rest of the figures very similar to my originals.
I will monitor the SNR today,but I'm more hopeful.
Did change the filter on the socket the router is plugged into, but whether that could have made any difference I don't know.
This just leaves one question - why is my upstream speed still so low? Any chance the PN DC team could pick this up?
John
JayG
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Re: Low SNR/connectivity issues

Are you sure the upstream figures in your first post are correct?
They show the same figure for both the sync speed and throughput speed, which shouldn't be the case.
When I was on ADSL1 I used to get a pretty consistent 360kbps upsteam with a sync of 448, so your 374 doesn't look slow to me.
jab1
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Re: Low SNR/connectivity issues

Those figures are correct - I'm not sure what the significance of them is, but if anyone on the DCT picks up on this, I may get an answer. As a point of interest, I've no idea whether I'm on ADSL1/ADSL2/20CN/21CN.
John
jojopillo
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Re: Low SNR/connectivity issues

Hi jab1,
You're on ADSL2+. I've just placed an order to uncap your upstream. That should complete tomorrow.
Jojo Smiley
jab1
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Re: Low SNR/connectivity issues

Jojo - you're as wonderful as they all say you are.  Wink
Thanks
John
John
jojopillo
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Re: Low SNR/connectivity issues

Tell me that when it's completed successfully Smiley
jab1
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Re: Low SNR/connectivity issues

OK - you're as wonderful as they all say you are - job done  Cheesy
BUT - now can you solve another problem I mentioned in my original post - download SNR dropping through the floor in the evening ?
I hadn't really noticed this until about ten days ago, probably because I hadn't been using the PC much in the late evening, but the cut-ff seems to be getting earlier & earlier - last night the download SNR dropped to around 18.15d 3.9/4.0dB at approx 18.15 and I couldn't get it to come back to a usable level, even if I tried a resync, as suggested by Oldjim.
Any chance of working your magic again?
John
John
jojopillo
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Re: Low SNR/connectivity issues

Hi John,
I'll make some changes to try to combat this, but it takes 24 working hours, so it'll be Monday before you see any difference.
Jojo Smiley
jab1
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Re: Low SNR/connectivity issues

Thanks Jojo  Cheesy
John