Desync?

Ive tryed to play Kickstart 3.1 (40.069) (A1200) (Commodore) (1993) with my brother. The Game desyncs at the moment we start playing.
We tryed both hosting ourselves and joining a server.

How can we solve that Problem?

make sure you got the same savedisks, and configs. leave settings for hoster - if you join don t press anything, just let your brother do the job, until you got your team screen.

We us the same savedisk ( C P ed it )
We use the same settings ( ^ )
Host - Joypad 1 - Keyboard A - Joypad 0 disabled
Guest - Joypad 0 - Keyboard C - - Joypad 1 disabled
Tryed with Kaillera Server P2P

The online difference was that he Maximized the window.

Any idea ?

I d also say your versions aren t exactly the same. Are you sure both your HDF files are the same too? Maybe try to play against someone else and see if it works fine.
Multiple desyncs can also indicate a connection problem, but to happen everytime just after you start playing it s really not likely.