Does ISPCONFIG 3 enforce limit to the number of simultaneous website access or concurrent connections to the server either by SSH, FTP by each client? This is to prevent web hosting clients overloading the server.
ISPConfig does not apply such Limits, but you can set them in the config files of the services that you want tolimit. You can use e.g. mod_cband for vhost based limits in apache andconnection limits for pure-ftpd are the settings MaxClientsPerIP and PerUserLimits and for ssh you might use MaxSessions and MaxStartup.