Either you set up IP address or creat DHCP client on ether5 to get the IP from your ISP. You can bridge other ports and assign private IP address for it. Create DHCP for that bridge. Create masquarade for ether5 or private IP range.
Everything is described here
. The only thing to remember is to switch ether1 (as in manual it is gateway port) with ether5 (which you want to use as gateway).
And I believe you ment "hAP ac" not "wAP ac" or "wAC AP" (which doesn't exist at all).