DG834G - strange problem

I have a Netgear DG834G and a Plusnet 512k ADSL connection. I use this
with a combination of wired and wireless computers. I have a 3Com
8-port hub which is connected to port 4 of the DG834G which then feeds
my two desktops, a print server and a computer in my neighbour's house
as well as a few unused sockets. My laptop is connected via 802.11g

Recently I've noticed problems with the connection dropping out and
taking ages to reconnect. Whilst trying to isolate the problem (and it
might have always been like this all along) I've noticed my noise
margin (downstream) has been very poor, sometimes 2-6dB at best. In an
effort to improve this I've checked all internal wiring, remade
connections, replaced the filter etc without any difference being
noted.

I eventually found that with the hub disconnected from the router the
ADSL connection syncs up straight away and my noise margin is about
20-22dB.
As soon as I reeconnect the hub the noise margin drops again.
I replaced the hub with another 3Com hub (a 5 port) and the problem is
not as bad and the setup is useable. However it still takes a long time
to sync up.

What I can't fathom is why the LAN side of my router has any effect on
the WAN side. Why should syncing take so long with a hub attached ?

My next step is to try another (non 3Com) hub or switch to see if it's
some strange incompatibility between 3Com and Netgear.

Any ideas anyone ? Anyone seen anything similar ?

In an earlier contribution to this discussion,
sasquartch <(E-Mail Removed)> wrote:

> I have a Netgear DG834G and a Plusnet 512k ADSL connection. I use this
> with a combination of wired and wireless computers. I have a 3Com
> 8-port hub which is connected to port 4 of the DG834G which then feeds
> my two desktops, a print server and a computer in my neighbour's house
> as well as a few unused sockets. My laptop is connected via 802.11g
>
> Recently I've noticed problems with the connection dropping out and
> taking ages to reconnect. Whilst trying to isolate the problem (and it
> might have always been like this all along) I've noticed my noise
> margin (downstream) has been very poor, sometimes 2-6dB at best. In an
> effort to improve this I've checked all internal wiring, remade
> connections, replaced the filter etc without any difference being
> noted.
>
> I eventually found that with the hub disconnected from the router the
> ADSL connection syncs up straight away and my noise margin is about
> 20-22dB.
> As soon as I reeconnect the hub the noise margin drops again.
> I replaced the hub with another 3Com hub (a 5 port) and the problem is
> not as bad and the setup is useable. However it still takes a long
> time to sync up.
>
> What I can't fathom is why the LAN side of my router has any effect on
> the WAN side. Why should syncing take so long with a hub attached ?
>
> My next step is to try another (non 3Com) hub or switch to see if it's
> some strange incompatibility between 3Com and Netgear.
>
> Any ideas anyone ? Anyone seen anything similar ?

I bet your 3Com hub uses the same switched mode power supply as my 3Com
router. *That* is the likely cause of your reduced noise margin. Try
powering the hub with a generic non switched mode power supply and see what
happens.

When I had problems with my 3Com router losing synch with the ADSL line
after it been on for 30 minutes or so, it (the router - but not the power
supply) was replaced under warranty. The new one was no better! But as soon
as I replaced the power supply with a different (non 3Com) jobby, it was
fine.
--
Cheers,
Tim
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