Block IP address

Dear All, Could you please help me the solution I’ve been finding for months.

I’m using Routerboard 750, V2.38.

I connect all my computers 192.168.1.1/24 with port1. I wonder if I want to block computer A , 192.168.1.10/24 to communicate with computer B 192.168.1.11/24

Please Help!!!

Thank you.