Hi xemon,have you tried to set up a Network zone on PC2 using the mac address of PC3 then use the “Stealth Ports Wizard” to allow access to that zone/pc
Firewall/My Network Zones/ADD/A New Network Zone/Call it PC3/APPLY
Highlight “Add Address Here”/Add/A New Address/Check A MAC Address/Enter PC 3`s MAC address/APPLY
Now Stealth Ports Wizard/Next/I would like to trust an existing “My Network Zone”/from the drop down highlight PC3/Finish
You should get the message “Your firewall has been configured accordingly” and in Firewall/Advanced/Applcation rules(under System) and in Global Rules(at the top) there should be 2 rules.