masterserver can't ping me - I need to forward ports

[Suokkola]

does anybody know what means "WARNING: master server registration failed: failed pinging server" that message comes always in the command line server after "looking up assault.cubers.net"

[Gibstick]

Your server could not be reached by the masterserver. Check your firewall and forward your ports from your router. By default, AC uses ports 28763 and 28764 UDP. See the wiki article for more information.

[Hellspell]

I have the very same problem, although only yesterday my server was working correctly