Seems that network mode doesn't work on Mac OS X yet. Wether local nor on real networks...
Tested with Simutrans Nightly r3720 on Mac OS X 10.6.4 running on Intel i7 Platform.
HOw did you tested?
The joining dialog will not work on any system. Could you download a server list?
Tested it over "Load Savegame" dialog and "dialog_tool[28]"...
I tried to connect to Franks Testserver over network, to an other server on my LAN and to the localhost... Nothing works.. "Server antwortet nicht"
And yes, i can download the server list, but the rest of the dialog is useless...
If the list download work, then there is hope. I will look into it anyway, I was on conference since today.