What does Restrict Administrative Access (Home > Tools&Settings > Restrict Administrative Access) option do?
Which users are affected by enabling option Restrict Administrative Access?
In Plesk, it is possible to prevent administrative access from specific IP address or addresses.
Anyone trying to log in to Plesk as an administrator from a disallowed IP address will see an error message.
Restricting administrative access to Plesk does not prevent resellers or customers from logging in to Plesk, even from disallowed IP addresses.
For more detailed information refer to the Plesk Documentation: Restricting Administrative Access