Sky ADSL dropping out every five minutes

We switched to Sky ADSL after three years of perfect BT service.

It worked fine for two weeks but now ADSL keeps losing the connection -- the @ symbol goes red on the front of the router. It then reconnects but loses the connection again a few minutes later. Sometimes it stays online for maybe 10 hours, but then the pallaver starts all over again.

Remedies attempted:

- changing the microfilter -- did no good (tried three separate ones)
- removing all phones/devices from phone sockets -- did no good
- resetting the router to its default values (including resetting the Wi-Fi name/password grrrrr) -- did no good
- trying a different ADSL cable from the socket to the router -- did no good
- Sky's tech support has tested the line and found it to be fine, I'm currently "escalated" and waiting for a response from them

When the disconnect/reconnect is happening there's noticeable crackling on the line, but the line is usually very quiet indeed.

Some details and stats for you:

System Details
Manufacturer Sagemcom
Model Number F@ST2504n
Firmware Version 5.23.1a4N
ADSL Firmware Version A2pD030n.d23b
Modem
Modem Status Connected
DownStream Connection Speed 7007 kbps
UpStream Connection Speed 605 kbps
VPI 0
VCI 38

Network Type PPPoA

Line Attenuation 36.5 dB 22.0 dB
Noise Margin 6.3 dB 7.0 dB

The connection speed is low, but difficult to know if that is a Sky DLM cap or a line issue capping you. Tempted to say its a Sky DLM cap based on both downstream and upstream being a little low.

(http://www.coolwebhome.co.uk/calc/calculator.php will show what the expected performance for the line is)

Did you try at the test socket? This removes the effect of the ring wire, and other problems created by the extensions.

If you were on ADSL (up to 8 Meg) with BT, then being on ADSL2+ via Sky is probably showing up issues that were masked by the lower performance requirements of ADSL.

Alas the Sagem router does not let you force the ADSL type, which can be an easy way to overcome instability sometimes. Suspect Sky may just slow the connection down until it becomes stable.

Thanks for the comprehensive reply!

Sadly I can't remember the connection speeds with the BT router. I did notice that things seem to get quicker when we moved to Sky though -- I was surprised how quickly a BitTorrent came down the line, for example.

That said, none of us in the household download much, and we'd be perfectly happy to sacrifice speed for a stable connection.

The BT box is old (early 90s logo) with a full rather than half plate. I'm not even sure if that's the main one or an extension, because there's another (unused) socket in the hallway near the front door. Could be worth a try in that socket, I guess!

Edit: The router is now in the hallway socket, and the attenuation/noise margin aren't much better than they were, and the speed is now 7000Kbps.

ADSL Link Downstream Upstream
Connection Speed 7006 kbps 605 kbps
Line Attenuation 37.0 dB 22.2 dB
Noise Margin 5.9 dB 10.1 dB

Edit 2: No matter what I do it seems we're now limited to 7000KBps, so it looks like you're right -- the Sky engineers are limiting the speed.

Edited by deleted (Tue 04-Dec-12 13:51:53)

Your SNR margin is very close to the target margin. The crackling on the line indicates a line fault which needs fixing. I think you need an engineer visit.

Edited by deleted (Tue 04-Dec-12 15:45:15)

This situation is not that uncommon with Sky, as their DLM does two things

1. Caps to a sync speed rather than a target margin
2. Uses power backoff to save power, and thus a line that can go faster does not always show lots of spare margin as with other providers

That may or may not be true, however in this case there is obviously a line fault. It also looks like the line may be syncing as ADSL not ADSL2+.

I'm not sure if it's worth noting but a few weeks ago a couple of my neighbours were complaining about having no broadband, while others (including me) said it was fine. In the following days a couple of BT broadband vans were parked on the street.

Problem at the exchange? I'm in Urmston, Manchester. We don't have fibre here as far as I know.

Incidentally, to show how random this can be, at the moment the up time since the last disconnection is 17 hours. Still at 7Mbits.


ADSL Link Downstream Upstream
Connection Speed 7007 kbps 605 kbps
Line Attenuation 37.0 dB 22.3 dB
Noise Margin 8.1 dB 15.4 dB

Edited by deleted (Wed 05-Dec-12 10:43:09)

Happen to remember your stats from a few weeks ago, i.e. have they changed significantly?

I am using the same Sagem router as you and I had the same trouble as you back in September this year with my connection dropping.

I was using the 2012 version of the Sagem router but after a phone call to Sky they sent me an older model (2011) and this has worked flawlessly.

The only difference I can see is that the version I'm using now has PPPoA as my network type where as the 2012 version used MER (I think)

Have you asked Sky to replace your router if it's within it's 12 month warranty ?

They replaced mine free of charge.

They're both identical?

The 2012 router is a sky hub but the Sagem 2504n is identical from last year and this.

A fibre version was released but that's identical with slightly different firmware. I can say I've tried every sky router from the 2nd one upwards

ADSL wise both are identical products

Edited by ukhardy07 (Fri 07-Dec-12 04:30:06)