Super high(?) noise margin, but intermittent connection

[stillStruggling]

Hi,
I wonder if you can help. This post will be quite detailed, so bare with me.

I'm writing on behalf of a friend, I'm supposed to be the computer literate one between us.

Here is the situation. He has just had sky broadband put in (few weeks). All was working fine for a while. He's started to lose connection intermittently. When I went round, his connection was fine. Stable, and pinging google.co.uk with a ping -t reported 0% packet loss. When his connection is "down", the ping response is not so good, 25%,50%,75% (just a single ping, no -t).

I'm convinced the computer is fine (XP home, Dell, Clean - no junk installed).

When the connection was good, these were the stats from the router:

Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 7709 8714 0 324 1312 01:30:31
LAN 100M/Full 11159 9983 0 1376 355 01:43:58

ADSL Link, Downstream, Upstream
Connection Speed, 2048 kbps, 320 kbps
Line Attenuation, 45 db, 13.5 db
Noise Margin, 15 db, 7 db


Tonight with no connection, I got him to read out the stats over the phone:

ADSL Link , Downstream, Upstream
Connection Speed, 2048 kbps, 256 kbps
Line Attenuation, 45 db, 13 db
Noise Margin, 14 db, 1 db


Can I guess its the 1db on the upstram, that is my problem?



His set up is as follows:
To his master socket he has an extension lead plugged in. This runs in to the back room where it's connected via a filter to his computer (and 56k modem).

The extension lead connector at the master socket end allows another phone device to be plugged in to it's "back". To it's back it has a filter plugged in. A splitter is plugged into the filter, and a phone and sky box is plugged in to that splitter.

If the 56k modem wire is not plugged into the pc, the downstream noise marrgin is about 14db. When it IS plugged in, it jumps to 25db. Can this figure be TOO high?

From what I can gather, these figues are ok. The only suspect thing I can see is the 1db upstream. But what would change that? I thought it was the downstream that was important.

Any ideas / advice greatly appreciated.

David.

[Saturday]

Poor upstream noise margin (compared to downstream) is generally a symptom of a line problem - most often a filter problem but extensions and faulty devices attached can also cause this.

I can't completely follow your description of the wiring and filters but it sounds a mess. I suspect the problem lies there. Avoid extensions if possible, splitters too and don't ever plug a splitter into a filter. What you must have is an unfiltered connection to the router - everything else must be filtered.

[stillStruggling]

Hi,
I've done a sketch (excuse the scale)... the letters are just to identify the different parts. Does this make it clearer? Can you see a mistake?

Are you saying there should be no filter between the master socket and the extension to the router?

Thanks,
David.

[moleman]

You show the sky box as plugged into the same filter as the house phone.

If this is in the RJ11 side of the filter then it is unfiltered. It must go into the BT phone socket side of the filter.

EDIT:
Actually I've just re-read your original post and I see you have a splitter in there so please ignore this post.

[Smithy99]

Easiest way to test this is to move the router to the master socket and connect it via the test socket (remove the lower half to the master socket to access it) then either connect an ethernet lead to the PC or use wireless to see if that improves things. If it does then the internal wiring is at fault, if not there may be a line fault.

[IAmNotTheEnemy]

its a bug with the phase 2 Netgear routers...it doesnt train at the right upstream and block access/makes it very slow...

CST need to set it to 416kbps and it'll be fine...

[Isitme]

I think it is more likely to be the long phone extension, which is probably a low quality flat wire type that is causing the disconnections. The easiest way to fix it would be to plug a filter directly into the Master socket and use a good quality 10m RJ11 cable to connect to the router. Run everything else from the filtered side of the plug in filter. An ADSL faceplate would be tidier, but hardly necessary if there are no hard wired extensions from the Master socket. With Broadband there is no need to have a Dial up Modem permanently plugged in. Disconnect it and only plug it in when and if it is required. Your sketch shows this connected to the router, which I assume is a mistake.

One other point, is the Sky box connected through a filter? The box on the extension supplied by Sky TV fitters is a splitter, not a filter, although some look like a filter.

[IAmNotTheEnemy]

it is also a bug in the Netgear Phase 2 routers...seems to be affecting Base customers who's upstream syncs at 256kbps as opposed to 384 and stops you getting online - unless CST set it to 416kbps and then you're fine...

seems to be something with the FW - perhaps the V1s are now affected since the new FW...