cancel
Showing results for 
Search instead for 
Did you mean: 

Back to the Future?

pvmb
Rising Star
Posts: 263
Thanks: 17
Fixes: 1
Registered: 12-02-2014

Back to the Future?

After having two long lasting intermittent line faults cleared a while ago I have enjoyed a happy, trouble free period of ADSL 2+ broadband with a clean line and ~18 MBps sync speeds.

 All things come to an end (especially on Broadband) and over the last couple of days I have been experiencing irritating and repeating Internet dropouts. Currently there is no obvious line problem causing this (though I am now monitoring). In some cases it even possibly looks like blocking of the WiFi channel. But presumably not when the router Internet light goes red and I eventually reconnect with a new IP address.

I see others here claiming much the same problem. Does anyone know if there is some problem on the remote side? Gateways etc?

See here

12 REPLIES
pvmb
Rising Star
Posts: 263
Thanks: 17
Fixes: 1
Registered: 12-02-2014

Re: Back to the Future?

Internet currently more or less unusable.

I am seeing a big leap up in CRC Errors just before the line drops. Nothing else, apart from very large number of bit swaps.

 

Later:

Changed filter. Speed now dropped by 4Mbps on router restart. DS SNRM gone from 3 to 7dB. Clunk! :-(

Just gone back down to 3dB DS SNRM, but speed unchanged of course. Is there hope? Very different Bitloading spectrum...

 

Later:

It's going gaga. DS SNRM 3dB; 7dB; 3dB; 7dB; 3dB; 7dB...

Superuser
Superuser
Posts: 9,975
Thanks: 1,508
Fixes: 19
Registered: 22-08-2007

Re: Back to the Future?

That does rather sound like RFI. SNRM going from 3 to 7 to 3 dB (at a lower speed) somewhat implies the presence of 4dBs worth of noise - the noise having abated when the SNRM rose to 7dB and restarting when it again (without a resynch?) fell to 3dB.

Which router have you got?

Feel up to running router stats monitoring? See links below.
pvmb
Rising Star
Posts: 263
Thanks: 17
Fixes: 1
Registered: 12-02-2014

Re: Back to the Future?

The router is standard Plusnet Technicolor TG582n. I am running DSLstats.

This has only started happening in the last few days. I don't know whether coincidence or nor but the whole area where I live is being cabled up by Virgin Media. Though this has been going on for some weeks, of course they may only recently have been switching on and testing. I don't know.

pvmb
Rising Star
Posts: 263
Thanks: 17
Fixes: 1
Registered: 12-02-2014

Re: Back to the Future?

DSLstats PIC.gif

 

 

 

Superuser
Superuser
Posts: 9,975
Thanks: 1,508
Fixes: 19
Registered: 22-08-2007

Re: Back to the Future?

That is the most odd SNRM plot I have ever seen.  I am mindful of the possibility that what is shown is an artefact of the measuring tool.  Personally I prefer Router Stats if only for the fact I know its failings.

If I believe everything that plot shows I have to conclude...

  • There are two sources of interference
  • One is of short duration (the downward spikes) of -3dB **
  • The other has a long decay duration
  • During the period being plotted the TARGET SNRM changed to 6dB
  • After the re-synch at 6dB the background noise abated resulting in a SNRM of 9db

@Gandalf - are you able to confirm if there has been a change in TARGET SNRM please?  Can you also post a VR plot please?

 

davidj66
Rising Star
Posts: 595
Thanks: 29
Fixes: 1
Registered: 04-09-2008

Re: Back to the Future?

Had similar varying noise levels when Openretch were installing the fibre cab. alongside the "old" cab. Went back to normal after they finished.

Plusnet Help Team
Plusnet Help Team
Posts: 4,001
Thanks: 844
Fixes: 207
Registered: 21-04-2017

Re: Back to the Future?

Hi there,


Sorry to hear you're having connection problems.

Apart from the instability around noon, your connection seems pretty stable.

 

Having said that, your SNR margin is higher than I'd expect...

 
  Upstream DSL Link Information Downstream DSL Link Information
Loop Loss: 14.8 28.5
SNR Margin: 6.0 9.6
Errored Seconds: 1 0
HEC Errors: 0  
Cell Count: 381759 1087401
Speed: 1244 14823

 

...especially since the SNR target is set at 3db still

Profile Info: WBC 160K - 24M Medium delay (INP 1) 3dB Downstream, UC Low delay (INP 0) 6dB Upstream (ADSL2+)

 

My tests aren't identifying any causes of that. I'd recommend running through the checks here, try a different router if you can, and then report the fault to us at http://faults.plus.net if things keep dropping.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
pvmb
Rising Star
Posts: 263
Thanks: 17
Fixes: 1
Registered: 12-02-2014

Re: Back to the Future?

It's just dropped again. Reconnected at sync ~18 Mbps and 3dB DS SNRM. 'Normal' Bitloading returned.

Went for a stroll earlier, couldn't see any electrical work going on just contractors still working on pavements further up main road away from my cabinet.

Will continue monitoring. Thanks.

Superuser
Superuser
Posts: 9,975
Thanks: 1,508
Fixes: 19
Registered: 22-08-2007

Re: Back to the Future?


Gandalf wrote:

Hi there,


Having said that, your SNR margin is higher than I'd expect...

 

 


...which would tie-in with he synch speed being 3Mbps (or so) slower than might be expected for a line having the reported attenuation.

I would suspect that there was a significant level of noise present at the time of the previous re-synch ... when the noise abated the SNRM rose 6dB. 

pvmb
Rising Star
Posts: 263
Thanks: 17
Fixes: 1
Registered: 12-02-2014

Re: Back to the Future?

Hope I am not tempting fate but, judging by today and yesterday, the problem has disappeared as mysteriously as it originally appeared out of the blue.

Superuser
Superuser
Posts: 9,975
Thanks: 1,508
Fixes: 19
Registered: 22-08-2007

Re: Back to the Future?

Plusnet Help Team
Plusnet Help Team
Posts: 4,001
Thanks: 844
Fixes: 207
Registered: 21-04-2017

Re: Back to the Future?

Happy to hear that!

Fingers crossed it isn't REIN.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team