This is not a bug. It means that the server had 4 or more slots earlier and the admin changed it to 2. No new players can connect, but the players on the server remain on the server.
Quote from zeugnimod :This is not a bug. It means that the server had 4 or more slots earlier and the admin changed it to 2. No new players can connect, but the players on the server remain on the server. i kno.... thats why i edited :nvm