Oh and BTW, I reconnected my homehub yesterday evening, and can confirm that it also has the same slow download speeds.

It will have.

Once you find the line stats, taken immediately after a reconnection, I think we will find it is at least 12dB. That will be because of whatever happened.

Sorting that is another story, as you will see or have seen on my website, in the Troubleshooting section >> high noise margin.

Thanks. I'll connect when I get home, and report back the noise stats.

Hi.

So the router has been turned off for 20 hours or so. I just reconnected, and same poor connection speed.

In the router status, I can see the following stats:
ADSL Link Downstream Upstream
Connection Speed 4525 kbps 888 kbps
Line Attenuation 21.0 db 8.4 db
Noise Margin 16.1 db 15.6 db

RouterStats Lite is showing the same noise margin.

Is this something that will just fix itself over the next few days, or do I have to contact BT?

looks very much like you have a problemo

give it time and robertos and the rest of the hit squad will pass on there advice

In reply to a post by bbawden:

Hi.

So the router has been turned off for 20 hours or so. I just reconnected, and same poor connection speed.

In the router status, I can see the following stats:

ADSL Link	Downstream 	Upstream
Connection Speed	4525 kbps	888 kbps
Line Attenuation	21.0 db		8.4 db
Noise Margin	16.1 db		15.6 db

RouterStats Lite is showing the same noise margin.

Is this something that will just fix itself over the next few days, or do I have to contact BT?

There you can see the downstream noise margin was 15dB or 18dB at the time you connected. Assuming BT is your ISP, from the fact you have a Home Hub, if you are lucky you will be able to get them to do an SNR Reset.

That will cure the low speed within a 2-3 days of them doing it. (It causes a new 10-day training period like you had originally).

If you are not lucky and they won't do one for you, then see Section 4 of this page.

Each 3dB above 6dB costs you at least 500kbps and possibly 1200kbps. SO that's where your long-term speed has gone. The short-term is of course controlled by the IP Profile which I hope you know about by now.

Thanks for your help, I really appreciate it.

I'll ring BT in the morning, and see if they can do a SNR reset for me.

what would have caused it to be at this level in the first place

In reply to a post by andyboygsi:

what would have caused it to be at this level in the first place

Probably lots of reconnections and messing around in a short period when he was trying to get going with his Netgear. Been there - done that, myself.

The trigger for at least a single step rise in target noise margin is 10 times in an hour, but it does seem to make bigger jumps in most cases. Goodness knows what actually happened. Only the OP may have any idea, but was almost certainly ignorant of this effect at the time, and has no chance now of remembering.

If the line was unstable now then we would need to be looking at the ongoing reason. But it seems to be stable, just the DLM settings messed up.

Yeah, I think that's it. I was changing the settings a lot and it's quite possible that the router reconnected 10 times in an hour.

I spoke to a very helpful person from BT who obviously knew what they were talking about, and more importantly knew that I knew what I was talking about. (there's nothing more frustrating than you knowing the problem is A, but the support making you try solutions B-F first!)

So they triggered a DNR reset on my line, and reset the training period. This was about 8pm last night. They said I should see the noise margin start to decrease, but it may take 10 days for the line to stabilise back to where it was.

I'm looking now, and the noise margin is still up at 18db. Should I have seen a decrease yet? Do I need to do something at my end, or just be patient?