I'm using a HAP AC2 as a home router with a cable modem.
I've enabled uPNP in IP -> UPnP Settings, and ticked 'Allow To Disable External Interface' and 'Show Dummy Rule.'
I've added ether1 (WAN cable modem) as External, and all other ports and wireless LANs as internal.
However I don't see any uPNP rules appearing in the various firewall pages. I'm running Skype which usually requests these ports.