Creating a new LAN switch in a 730 appliance

[gadibe]

Hi everyone.

My purpose is to create 2 separate networks with both to be able to access internet, but there will be no connection between the 2 networks (never did this before). So i connected an additional switch to the LAN6 port of the 730 appliance. Then a moved the LAN6 to the separate network. That moved it out of the default LAN1 Switch and created a new subnet with a functioning DHCP on it. But a laptop connected to the new switch still can communicate with an original network. So i thought maybe i need to create a LAN2 switch, but then i get an error "Switch cannot be added because no networks are available to assign to it". Now i'm stuck.

Please help?) What is the right way to do it?