Comment 2 for bug 375745

I am getting the same error, both with the default Ubuntu 9.04 install of pioneers 0.12.2-4 (sudo apt-get install pioneers) or with a build from source.

To reproduce this error:
1) Start the client
2) Press "Create game"
3) Press "Start server"
4) Press "Join private game"
5) Make sure the fields are set to "localhost" and "5556"
6) Press "OK"

The messages frame now displays:
17:04:59 Connecting to localhost, port 5556
17:04:59 Error connecting to host 'localhost': Connection refused

Workaround:
1) Instead of "localhost" type 127.0.0.1

In addition, the "Add Computer Player" in the button does not appear to work. It does add the players, but none of them are really connected to the game.