You can set the maximum number of connections to the Server at the Site level. With multiple Sites, this means that some Sites can allow more users than other Sites.
The Max concurrent socket connections check box limits the amount of socket or low-level connections allowed by the Server. When this limit is reached, any subsequent connection attempt generates a socket or network error in the client. It reacts as if the Server is not available, because the Server refuses the connection entirely. For a Server configured as an anonymous FTP server, it is recommended to limit connections per user. In this case, the Server will allow the user to connect partially before being told that the Server is full or busy - a more graceful way of denying the connection.
To restrict the number of socket connections
In the Administrator, connect to the server, then click the Server tab.
In the left pane, click the Site you want to configure.
In the right pane, click the Advanced tab.
Select the Max concurrent socket connections check box, then specify the maximum number of users you want to allow at any given time. If the box is cleared, the Server does not restrict the number of users.
Click Apply.