The IP on whatismyip.com is exactly the same i entered as static IP. Firewall and
forwarding (not needed, see above) can't be the issue as it worked with the same settings after manually entering my IP. Maybe the was another bug, I'll reopen the server now with automatic IP, please check if you can connect.

The "crash" Memorix described was that I had to forcefully shutdown the server with ALT+F4.
On pressing 'enter' (while i was searching for a player list or scoreboard) the game minimized into a tiny window with only a tenth of the screen showing . I couldn't get back to fullscreen and i couldn't use the menu, so I had to shut down the server.

However, don't loose faith here! I can see your game will be great after issues have been worked out! And I haven't played much singleplayer yet, thats another highlight!