Speed up and down

Hi all! Over the past couple of days my ADSL connection (provided by Vispa) has been very up and down. Most of the time it's very slow - speeds in the 56k modem range, however there are periods where it'll be somewhere near normal. This graph, which I've nerdily produced, shows ping times to Google - as you can see, the ups and downs are very regular (the spikes are timeouts).

http://img215.imageshack.us/img215/8898/pingjk.jpg

I've been on to Vispa who state there's nothing wrong with the line and that my stats seem fine. (They don't traffic shape or ought, and anyway I've used way more in previous months than I have this month and I'm nowhere near my limit). I've tried the engineer's socket and replacing the filter, none of which has made anything any happier.

Anyone have any idea what could cause this? I've not had an internet connnection behave like this before. It's the same on all the computers and mobile devices in the house. The next step is to get a BT engineer out but that'll cost me if they don't find anything wrong at the exchange, so I want to rule out any other potential problems.

Thanks for any help!

MD

In reply to a post by Masterdog:

my stats seem fine.

Which are what?

If you graph is accurate, that's a very orderly series of drops.... could it be electrical noise causing this ?

"The next step is to get a BT engineer out but that'll cost me if they don't find anything wrong at the exchange, so I want to rule out any other potential problems."

Your CP is being 'economical with the truth'. It's not just exchange cased faults that waiver the charge. Line faults also come as a freebie. In fact, it's only at the CP's discretion if they pass charges on to you.

Sorry, meant the line speed which they've said is connected at 7616 with a throughput profile of 6500. Not sure how to read the stats at my end, which are...
Attn: 16 up, 14 down
Noise margin (which I assume is SnR?): 26 up, 10 down

In reply to a post by Masterdog:

Sorry, meant the line speed which they've said is connected at 7616 with a throughput profile of 6500. Not sure how to read the stats at my end, which are...
Attn: 16 up, 14 down
Noise margin (which I assume is SnR?): 26 up, 10 down

They don't look right. Have you swapped the Attn and the SNR numbers?

In reply to a post by Masterdog:

Sorry, meant the line speed which they've said is connected at 7616 with a throughput profile of 6500

But what does your router actually say?

In reply to a post by Masterdog:

Not sure how to read the stats at my end

Then why not just copy & paste them? Then you won't need to interpret them yourself.

My router said the same thing, although since I've connected to the engineer socket it's gone up to 8124, or something (I'm at work now and can't check it). The stats I posted were just a copy of those given by the router, but it's a not-great Belkin jobby so might not be giving me all the info I need. I'll try to post the full page later on.

In reply to a post by Zarjaz:

If you graph is accurate, that's a very orderly series of drops.... could it be electrical noise causing this ?

What kind of thing would cause the electrical noise? There's been no changes in the house recently, certainly nothing near the router. Or could it be something along the line?

If the connection remains at that sync connected to the test socket, then it's something in the house, possibly the extension wiring or filter which could be the cause. Seeing as you already replaced the filter, can you give a description of how many extensions you have please?

Edited by deleted (Wed 23-Mar-11 09:26:08)

In reply to a post by Masterdog:

In reply to a post by Zarjaz:

If you graph is accurate, that's a very orderly series of drops.... could it be electrical noise causing this ?

What kind of thing would cause the electrical noise? There's been no changes in the house recently, certainly nothing near the router. Or could it be something along the line?

7 minutes at a time, every 30 minutes. Is that pattern repeated 24/7, only in the evenings, only on weekdays, etc., etc.?

Heating system springs to mind.

It might be worth an evening of switching off (at the wall) everything electrical you possibly can - heating, lighting, the lot - and see if the pattern continues.

After that, I'd follow the route of the cable and see if you can see anything nearby that could be generating a lot of electrical noise.

Externally, you anywhere near trains, level crossings, pumping stations? Any factories (especially fabricators - all that welding is noisy)?

It happens 24/7 as far as I can see - I was downloading something which usually would take a few hours overnight the other night, and it wasn't even halfway done by the time I got up. It also happened all day during the weekend.
I'll try switching everything off when I get home. Oddly though, whenever I've restarted my router it seems to restart the pattern - I always get the 7-odd minutes of good connectivity followed by the 25 minute slowdown. If it was external you'd presumably expect that I'd turn my router back on during the middle of at least one of the slowdowns.
I'm in a quiet little village nice and near to my exchange - nothing heavy duty ever goes on here.

Edited by deleted (Wed 23-Mar-11 10:29:33)

In reply to a post by Masterdog:

nothing heavy duty ever goes on here.

Doesn't look like electric fence to me - pattern's wrong.

Can't be a level crossing or electric trains - too regular!

Noisy fridge?

Please reply re: alarms, oil tanks, and testing the extension sockets.

Have you tried a different router?

Okay, a bit more information. Turns out the problem only occurs when my main PC (connected via Ethernet) is on. When it's off, the internet performs normally. As soon as I turned on the main PC (and waited the requisite 7ish minutes), the problem came back.
I'm going to boot to an Ubuntu live CD to try and determine whether the problem is with hard, firm, or software. I did mess around inside the computer the other day so I'll probably poke around in there too.
Thanks for the help all so far...not had a problem like this before!

Hmm. Noisy switchmode PSU probably.

Could be either the PC or the monitor - does the monitor have a seperate power brick? Move the stuff as far away as you can from the router and it's cabling, and maybe try a surge filter on the mains supply to the router.

At least you know what the cause is.

Well it worked okay on the other devices when the problem computer was on but not connected to the router. It also seems to be running along very nicely at the moment using Ubuntu. Guessing it's a software or driver issue then?