There can be a situation in which you want users not to connect to the server
1. During server upgrade.
2. Bringing up the old server up for some reason.
Just enter the following command at the console
Set configuration Server_Restricted=1
Set configuration Server_Restricted=2
1 means that server is restricted for current session only & parameter is clear after server reboot.
2 means that the change is persistent & will remain after reboot as well.
Note:- The above commands will set the parameters directly in notes.ini file.