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High/variable SNR and speed reduction

FIXED
jab1
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High/variable SNR and speed reduction

Please forgive the large post, but I want to include as much useful data as possible.

I take 3 or 4 2 to 3 week holidays a year, and disconnect/turn off the router each time. On my return, I fire it up again and usually connect at something around 11.5Mb/s at a 6dB downstream noise margin, which holds for a couple of days, and then changes to 8.5/9.0Mb/s and 10/11.5dB. Not ideal, but for what I do, that is acceptable.

Previously, this has held between my intentional shutdowns, and I'm happy(ish).

However, I returned from a two week break on 01/11/17, and since then, the situation has become, to say the least, aggrevating.

To save more typing, I'm just going to insert some pictures.CLS.PNGConnectionSpeed-2017Nov01-2105.jpgConnectionSpeed-2017Nov03-1118.jpgConnectionSpeed-2017Nov20-1102.jpgConnectionSpeed-2017Nov21-1345.jpgConnectionSpeed-2017Nov22-0752.jpgConnectionSpeed-2017Nov23-1346.jpgNoiseMargin-2017Nov01-2105.jpgNoiseMargin-2017Nov03-1118.jpgNoiseMargin-2017Nov20-1102.jpg

John
17 REPLIES
jab1
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Posts: 1,866
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Registered: 24-02-2012

Re: High/variable SNR and speed reduction

Last fourNoiseMargin-2017Nov21-1345.jpgNoiseMargin-2017Nov22-0752.jpgNoiseMargin-2017Nov23-1346.jpgRLog 15.05.PNG -promise

John
jab1
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Re: High/variable SNR and speed reduction

@Gandalf Any chance of you checking my connection, please?

John
Plusnet Help Team
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Re: High/variable SNR and speed reduction

Fix

Hi John.

It looks like your line is banded.

Profile Info: WBC 3M - 6M No delay (INP 0) 6dB Downstream, UC No delay (INP 0) 6dB Upstream (ADSL2+)

 

Testing your line isn't finding the cause of that and your connection seems stable.

 

I've removed the banding now. Can you re-test your speed in about 15 minutes?

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
jab1
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Re: High/variable SNR and speed reduction

Thanks @Gandalf - looks like it worked almost instantly, but I would still like to know what causes the problem referred to in my original post.Undecided

John
jab1
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Re: High/variable SNR and speed reduction

According to RouterStats Lite, I'm connected at 11987 Kbps. A test just run gives me an average speed of 9.87Mb/s, so I'm slightly happier Smiley

Also good to see I've reconnected with a 6.1 dB downstream noise margin - previous reconnections have been at 3dB, which is too low for the length of my line.

John
Plusnet Help Team
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Re: High/variable SNR and speed reduction

I'm glad to hear that worked.

I would still like to know what causes the problem referred to in my original post.Undecided

Testing your line didn't find the cause I'm afraid.

I'm looking further back on your connection logs and, by any chance do you switch your router off whilst you're away?

It's possible that those drops caused DLM to band the line.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
jab1
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Re: High/variable SNR and speed reduction

@Gandalf Yes, I do switch the router off when I am away for two or three weeks, from a safety perspective - all my electrical equipment, except the fridge/freezer, is switched off at the mains BUT the router is closed gracefully. As you will see if you read this thread from the start, on restart I get a connection speed similar to my current one (c.11.5Mb/s), but usually at a D/S SNR of 3dB, which I know my longish line can't handle, hence DLM kicks in and reduces the speed//racks the SNR up.

John
Plusnet Help Team
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Re: High/variable SNR and speed reduction

When I'm next in the office I could set a DLM threshold to try to prevent it from dropping the target SNR down to 3db?

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
jab1
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Re: High/variable SNR and speed reduction

If you could @Gandalf, I would be eternally grateful.

BTW - please excuse the tone of my previous reply, I've just had 'one of those' afternoons/evenings and feel a bit frazzled.Smiley

John
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Re: High/variable SNR and speed reduction

No worries John.

I've just placed the order to set the DLM threshold now, it should complete by the end of Tuesday.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
jab1
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Re: High/variable SNR and speed reduction

Thanks, Anoush - but I fear I do have a problem, my router has this afternoon reverted to a lower connection speed and higher d/s SNR.Sad

John
Plusnet Help Team
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Re: High/variable SNR and speed reduction

Yeah I noticed as I was testing the line too.

Have you tried the test socket?

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
jab1
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Posts: 1,866
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Registered: 24-02-2012

Re: High/variable SNR and speed reduction

@Gandalf.Methinks DLM is playing silly burgers - I had another resync back to 11.9Mb/s D/S SNR 6dB at 1607 (3 minutes after your post!)Huh

I haven't tried the test socket yet - my phone/power socket locations make this a last resort as I have to have wires trailing across open floors.

John
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Re: High/variable SNR and speed reduction

Hi John,

I trust that you've done all of the usual stuff ... QLT (at the time of the problems)?

What is the sample interval on RSL?

Are any of the transients associated with the use of the phone line?  Do you have a phone plugged in ... without which you'd have no idea if the events are associated with an inbound call.

I too suspect that there is an unfound gremlin here!

This looks like the TG582n router ... ?  Note that RouterStats can lose its way with these routers resulting in zero plots when the router is actually still connected.  Always wise to double check the router logs for xDSL down.