Network problem

[perkelt]

Hi all,

I've got 3 PCs, with the following conf:
pc1: icore2, 2gb ram, winxp sp2
pc2: ip4m, 2gb ram, ubuntu 9.04
pc3: ip4m, 1gb ram, ubuntu 9.10

I tried the following ottd versions:
cargodist
r18341 from binary download
r18341 from svn

When I'm playin' one of them pcs in single player, there's no problem.
When I start an ottd server, the game rum correctly and playable on the server pc, but the clients ran about 5 seconds, than freeze about 2-5 sec, ran again and freeze again, and so on... and it started when I try to view the network games and continue during map download and game running, also the game paused on the server too.

I checked one server and one client, one server and two clients, try to run the server on different pc, the problem is not solved.
I think, this was a network problem, so I tried to change the network switch (with different vendors too), the cables, but the problem not solved.
I checked the network switches in different network, and these are working correctly, and there are no problem. I checked the network throughput in different applications between these three pcs, like sftp, and it's working without freeze or any bandwith lost.

So the questions are:
What can I do to solve the problem?
What am I forget to check to isolate the problem?

[bigos]

Do you have same problem when you set server on 0.7.4?