And I also want to give some concept to you which about IP and VLAN.     Above is my router setting, you can found different VLAN ( A,B,C,D,E just make it easy reading ) can assign with same/different subnet.   You will found VLAN A,D,E assign with same subnet. Although they all in same subnet, but not all can communicate each other due to different VLAN, only same VLAN device can communicate each other, but all will route to same gateway, DNS and DHCP for assign I