Serverproblem: Players cant Connect, but DPmasterlist shows

[Jack]

Hi there!
I got a Problem with my Nex-Server:
I added a rule to the firewall to let trought port 26500 for nexuiz, but nobody can connect to that server.
but if i go to dpmaster serverlist and i manually edit ip:port (its sv_unpublic) the status is shown.
whats the problem with that server? i dont know what to do...