Internal network on m4300

Hi

I want to use the M4300 as an internal switch where all traffic is within the switch. This is because I will be connecting instruments to it and they should not be reachable by other pc. I created a new vlan and applied to some of the ports for testing. Unfortunately 2 pcs on the same vlan  cannot see each other  but they can ping the Vlan1 and the new vlan but no pc on the switch.

Have any tips on what needs to be done to use the switch for internal communication only.

Thanks for the help