This is very difficult to describe. It's like the connection to the
server pauses. The connection to the database is done via a VPN
tunnel. At some customer sites this works wonderfully and at some I
experience this problem.

If I'm connecting and downloading metadata (a query with a somewhat
big resultset to bring down to the client) or doing table compares in
IBExpert and I bring up the "Status Dialogue" for the VPN tunnel and
look at the activity counters - I can see that I am (the client, that
is) sending a couple of hundred bytes every say 0.5 seconds. The
server responds with a couple of hundred bytes with a somewhat longer
delay between them. This would be the "paused" state. Then suddenly
the server responds with *much* more data in every update of the
dialogue (I'm not an expert on packets and such) and that is when the
application on the client side behaves as it should. That would be my
problem description (sorry for being so vague).

But this small bursting negotiation-like seems to go on even though
theres no connection, no FB client software running, so the pauses may
be really silent on the FB part of the line.

One customer site has very long "pauses" between very short "non
pauses". Another client has short "pauses" and the "non pauses" are so
long that one even thinks the problem has gone away.

I'm stumped. These tunnels used to work great both with IBExpert and
my Client. The worst case is a 1.5.x database hosted on a separate
linux machine. I can see the behaviour with 2.0.1 databases too. When
I run the application I always use the 2.0.1 client library
(fbclient.dll) but when I run IBExpert I target the library to match
the server version. So that does not seem to be the problem.

Any takes? I really don't know where to start *at all*. I vaguely
remember something about NONAGLE, can that be it?

Lots of thanks,

/Dany