Ah, yes, hadn't considered the potential issue with powering it - can see how that might be awkward.

Do you only have 1 phone socket in your apartment?

Hmmm...

It's the simple, seemingly obvious questions that all too often highlight the assumptions we've quite unwittingly made. At the distribution panel in the flat there are 5 potential phone outlets. One is a conventional BT phone socket. The other 4 are housed in a single unit which is part of the Kerpen HomeNet data distribution system.

I've been trying to work out how they are wired up. If they are all daisy-chained, which they should be, then that arrangement should not be a problem. If they are not, it could be a significant part of the low speed syndrome.

The investigation continues, but not tonight - prior commitment.

Thanks for the question - good one!

once upon a time...
there were adsl routers that were usb powered, use one with a laptop, and no mains power required.

'Once upon a time... ' in another galaxy, far, far away?

Used to have one actually, Sagem F@st that came from some 'provider' who was trying to provide a service - and failed miserably. I didn't find it very satisfactory, and I wouldn't have a clue how to get the line stats off it even if I still had it.

(On the faint off-chance that someone is thinking of enlightening me, please don't... )

2 wires to the back of the master socket faceplate...

https://picasaweb.google.com/lh/sredir?uname=mygriff...

Apologies for the not very good quality, but it serves to illustrate the point. I've also included a couple of pictures of the adjacent hardware to show what I'm up against...

Now to work out how to run power to the router and locate the latter as close to the test socket as possible...

Cheers!

LOL! I don't see any 'incoming' wires. Much ado about nothing!

Hi again,

OK, I spent a busy couple of hours setting up and hooking up to the test socket. I was expecting to see better results with the lines to the phone outlets disconnected, but there was no significant change. In particular the the downstream attenuation came back as a rock steady 47 dB, which means I should be getting at least 5.5M. As it's LLU, it should be somewhat better than that.

I located the router close to the socket, and started off measuring the stats via the master socket, before switching to the test socket. I went through various permutations, including 2 filters and also no filter just for comparison. I logged the results with Routerstats-Lite from the DGND4000 Router, and the annotated trace can be seen here: https://picasaweb.google.com/lh/sredir?uname=mygriff... I was surprised at the changes following router reboots, and I don't really understand why that should be.

As you have said, this now should be the best I can get, and the line wiring downstream of the master socket seems to have no deleterious effect. This would seem to leave EMI and RFI as the likely culprits, so I shall now start prowling around with an am radio...

Deep joy

Thanks for your input - it has been very instructive.

It does seem that it isn't the house wiring causing the issues from that - unless the high target SNR is due to occasional interference picked up on the house wiring but that won't show up on this test. Getting the target SNR reduced to 6dB would gain you some speed - but it may go back again if there is something causing instability.

I can't remember - have you been monitoring SNR long term - if so do you get any significant drops at particular times?

Agreed tht the wiring appears to OK, apart from interference. I intend to prowl around with an am radio to see if I can get any initial indications of possible problems. Beyond that, I'm open to suggestions. With regard to reducing the target SNR, I've already discussed that with my ISP, and from the evidence of interference that they were seeing from their end it was clear that the interference needs to be addressed first.

I did monitor the line stats including SNR for about 36 hrs, I think. It didn't deviate much from 15 dB, but I'll post an image of the trace when I can get to the file (another computer).