frequent interruptions when connected over modem

[Christopher Woods]

>    thanks for the hints. I have indeed also tried SSH 
> tunnelling with even worse results (connection drops every 
> several seconds). The interesting point is that FTPing works 
> without drops (I downloaded a file from the same PC over 40 minutes).

I'm not intimately familiar with Orange Austria's 3G setup, but it might be
that you're being QoSed off the network :( In the UK, T-Mobile actively port
filter/block on their base packages, and NAT all connections (even if you
request a static route - no static IPs available). If you upgrade to a
premium package, you get unfiltered ports, but the traffic is still heavily
QoSed.

If you ping a known good server for the duration of your connection, what is
your latency (and does the TTL constantly change?) There could be a dodgy
hop somewhere along your route.

This might also be a question for Orange to answer - I know that you can
request (on my network provider, at least) the facility for PPTP tunneling
enabled, which means that there must be some element of QoS applied to allow
business-grade tunneling to proceed without problems. Talk about overkill
for a VNC connection though! (If you Remote Desktop / RemoteAdmin in, does
it give you similar drops?)