ssh hardly usable after login

[randall <randall@songshu.org>]

hi all,

have a peculiar problem for a few months already and i can't really
understand whats the problem here.

i have a debian machine in China and i connect coming from Europe, it
used to work perfectly after some driver issues that forced me to change
the network cards.

At the moment:
i can still login via SSH and issue commands,
but when opening a file with nano or issuing top it just hangs and
displaying a black screen until it times out.

i can copy to the machine via SCP but i can not copy files from it, it
just stalls till it times out.

a website served on the site can not be reached from the outside, it
connects but keeps waiting for response.

at the moment the machine functions as a router with 2 interfaces eth1
connected the LAN and eth0 facing the internet, there are no problems
occurring for the ones using it on the LAN side.

till so far my first hunch is that it is a firewall/routing problem, i
use shorewall. although i'm not really sure what it is.

so before i start to try disabling shorewall and or others and risk
loosing the LAN connectivity that actually is functioning i wondered if
somebody here has some clue on what this could be.

anyways, thanks all

Randall