copy from Clanforge news:
looks like SD like the option we pay for the servers and not they 
Clanforge News
New Dirty Bomb Gameserver Options!
Last updated on 25.10.2018 17:15:26 by [MP] Slyfox
Hi Multiplayers,
We will be adding an additional feature for the Dirty Bomb server owners, more information from the Splash Damage team on this here:
"We’re looking to get Dirty Bomb players used to playing on Community Servers, so we will be making all Community Servers joinable through the Quick Join button.
We know that some server owners will want to keep their servers private, so this option will be able to be toggled off from their control panel.
Servers that are password protected will remain unaffected."
To access this feature, login to Clanforge and after selecting your server select the ‘Settings’ tab,
we will be making the AllowQuickJoin feature available shortly.
Kind Regards,
Multiplay Support