If I set the max connection to 10 (for example), and 9 or more listeners tune in, Centova Cast reports the server as being down, and the "Server Administration" link and ShoutCast administrative URL at http://server.name:port stops responding.
This is not a bug, and it is not related to Centova Cast -- this is unfortunately just how ShoutCast works.
The "listener limit" in ShoutCast is actually a "client limit", and every connection to the ShoutCast server (whether it's an administrative connection to the "Server Administration" or http://server-name:port link, or an actual tuned-in listener) is counted toward that limit.
Once you reach that limit, ShoutCast will not allow any further connections of any kind, which is why Centova Cast thinks the server is down and the administrative link no longer works.
Unfortunately, because this is an internal "feature" of the ShoutCast server application, there is nothing that we can do about this as part of Centova Cast.