On my previous server it worked perfectly, created a server here and followed the correct steps again, doesn't work..
Their Wiki's basics: All CBSM connections will arrive from the IP: 126.96.36.199, 188.8.131.52, 184.108.40.206, 220.127.116.11, and 18.104.22.168 Step #1) Port Forwarding
In order to get started, you must know your IP address, and have the following ports forwarded/open.
This step can often be skipped for commercial hosts. You will still need to take note of your proper port numbers, however.
Game port (defined in serverconfig.xml) Game Query port (This port always becomes 'Game port + 1') Telnet port (defined in serverconfig.xml) Map port (This port always becomes 'ControlPanelPort + 2')
This means, that on a default installation, the following ports would need to be forwarded.
26900 (Game Port) 26901 (Game Query port) 8081 (Telnet port) 8082 (Map Port)