Each service has access settings.
Select your server in the Server app sidebar, then click Access.
Select the desired service from the Custom Access list.
Click the Action pop-up menu , then choose Edit Custom Access.
Click the “Allow connections from” pop-up menu, then choose “only some users.”
In the users and groups sheet, enter a user or group name.
To add more users or groups, click Add , then enter another name.
When you’ve added all the desired users and groups, click OK.