Re: difficult to isolate problem - browser access to router has problems on on machine but not other

[David Riebenbauer <davrieb@liegesta.at>]

* Arthur Marsh <arthur.marsh@internode.on.net> wrote:
> Hi, I've tried to run through all I can think of and am getting a bit stuck.
>
> I have two machines running Debian (one a dual-core Pentium4 with i386, 
> the other a quad-core AMD64-X2 with amd64), both with built-in ethernet 
> cards.
>
> The Pentium4 machine can access the browser interface of the adsl router 
> I use with no problems.
>
> The AMD64 machine has recently taken to stalling after entering the 
> username and password for the adsl router's browser interface, and I've 
> tried downgrading recent package upgrades, and different kernels and 
> browsers without success.
>
> However, the AMD64 machine booted with the sysrescuecd can access the 
> browser interface of the adsl router without problems.
>
> The AMD64 machine has a built-in Realtek 8169 NIC.

Not that I've got very much experience with network issues, but I'll
answer anyway. To me this still sounds like some ethernet issue.

I'd first if there are any oddities with the output of 
# ip addr

and 
# ethtool