Strange Loss of Internet Connection

My connection has been very reliable for the last year or more.
8096 on MAX DSL with up to 8 db SNR at best and normally not less than 6 db.

The Router is a Speedtouch 585 with 6.1.4.3 software and the ISP is Plusnet.

Starting a couple of months ago I sporadically lose connection or at least suffer apparent losses.

I use ADSL Monitor with 5 sec sampling [writing to RAM] and there is typically nothing obvious from the logs ie CRC errors or reducing SNR, to account for the �disconnections�.
I get lots of FEC�s which I assume are not significant.

On this occasion I suspected a problem because I got a warning on the Task Bar that I had limited connectivity and on checking, the Router Log had restarted displaying the time from reboot as a of few minutes previously.
Using the Router Web Pages I checked the �Internet� connection.

Everything was in order apart from the final entry labelled �Internet� which was shown as �X�.

Connectivity to Gateway (****************) - OK
Connectivity to DNS Server 1 (************) - X - down
Connectivity to DNS Server 2 (************) � X - down

The light on the Router for the Internet is showing green and I can access the Internet ok !!.

I�ve had other strange findings when losing �connection� and I�m confused as to what is actually happening.

The SNR is now rather lower than normal dropping to 5.5 whereas it had been around 6.5 to 7 before the problem.

Can anyone advise what is happening because at times I definitely do lose connection with the Router Internet light either off or showing red and the Logs confirm there had been a problem. At times rebooting the Router restores the connection but not every time.

Edited by deleted (Thu 17-Apr-08 17:26:58)

You'll probably have to post your router stats to get any useful input.

See http://www.dslzoneuk.net/adsl_line_stats.php

edited to add: plus FEC/CRC/HEC type info.

Edited by deleted (Thu 17-Apr-08 18:27:29)

In reply to:

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On this occasion I suspected a problem because I got a warning on the Task Bar that I had limited connectivity

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That would indicate a problem with the LAN or router. Dropping the WAN (internet) connection should not directly affect the connection between the router and your PC.

In reply to:

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and on checking, the Router Log had restarted displaying the time from reboot as a of few minutes previously.

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Again, dropping the WAN connection should not in itself cause the router to reboot.

I would suggest trying a different router if possible.
Has there been anything that could cause the router to misbehave or become damaged, like power surges?

This is the page I normally bring up which I think is the one in question.

http://i30.tinypic.com/2z4fehj.png

Edit Errors:

Checked the errors over the 2 hrs and 10 mins between powering up the PC and the problem:

CRC Down - 84
CRC Up � 0
Headers Down - 63
FEC�s Down - 1.56 million.

The Speedtouch Routers are/were notorious for the FEC errors they manage to count � so I believe.

Edited by deleted (Thu 17-Apr-08 19:40:05)

I've got another Speedtouch - 546 - if I remember correctly.

Its a long time since I dabbled but I think i may have to give it a go.

Many thanks

Yes, those are the stats.

You don't use DMT to tweak your SNR margin down do you?

It seems odd that your SNR margin hasn't been increased to try to stabilize the line.

If I remember rightly you can have 4000 FECs a second (or 31,200,000 in 2 hours 10 minutes) so your FEC count could be accurate.

I may have misunderstood panda�s comments but I am beginning to suspect that the issue hasn�t always been losing the Internet connection but the Router/Lan side has been acting up.

To the best of my knowledge and based on my records this problem has happened 12 times over the last six months � time flies.

I have been relieved and surprised, if not amazed, that on most occasions I have maintained my maximum sync speed of 8096 and only re-synced at a lower value four times. This could be consistent perhaps with not losing the Internet connection but down to a local issue.

I obviously don�t know how often this could have arisen when the PC is shutdown overnight but if it has it�s been very rare since I�ve never noticed it in the stats.

Having had my SNR Margin increased to 15 db in the past because of a BT cable fault I am very wary of having the margin increased again.
I think I�ll need a lot more losses of sync before the Margin is raised � at least I hope so.
It took my ISP 5 months last time to request BT to lower the Margin and I don�t want to go there again.

I have used DMT in the past with the 546 but that was over 12 months ago.

Thanks for the interest and help.

I get the impression it's the router rebooting causing the ADSL connection to drop, rather than the other way around.

I've no idea why the router would reboot apparently by itself, but if you can try a different router to eliminate it, that's a start.

I've dusted the 546 down and I'm waiting for the SNR to creep up a bit.

I'll have to do a bit of homework on the settings but with a bit of luck it will improve the situation.

If not I've got a couple more Routers one of which hopefully will resolve things.

I managed with one Router until MaxDSL came along and then things seemed got complicated.

God bless BT. Thank you.

Rather than start a new thread I thought it might be better to pick up this one.

I replaced the 585 with the 546 on the 20 th April.

For no obvious reason the Router seemed to re-boot on the 2 nd and 7 th May but has been OK ever since.

My concern or interest has moved to the number of CRC errors I now get on occasion.
I'm as certain as I can be that this has not happened before - I would have noticed.

On 5 or 6 occasions over the last few weeks these errors have been substantial.

Today between 17:55:10 and 18:17:15, ie 22 mins and 5 secs, the router recorded 5,847 CRC errors.
That�s 266 a minute.
The max in a 5 sec period being 37.

Are these figures likely to be realistic since I believe you lose sync if they are high enough and these seem pretty high to me.

This is an image of the period in question.

http://i32.tinypic.com/2vhvmlk.png

and the Router stats

http://i31.tinypic.com/ofbc.png

Edited by deleted (Tue 20-May-08 22:13:37)