If you lucky enough to have a UPnP enabled router or a NAT-PMP enabled router (Apple), Firewalla VPN should just work. In case it doesn't work, you will need to do a manual port forwarding. Basically, you need to map your router's public UDP port 1194 to Firewalla box port 1194.
Airport Extreme - Can you get this thing working? Because Nov 12, 2007 network - VPN Passthrough problems with Airport Extreme The problem was that the Airport Extreme router was configured to use the same range of IP addresses as the VPN, so while I was able to connect to the VPN there was some issues when trying to SSH into some of the servers where there was an IP conflict. It is possible to change the "IPv4 DHCP Range" in the advanced network options of the Airport
Routers - FreeSWITCH - Confluence
The best Wi-Fi replacements for Apple AirPort routers A network punch-through protocol called NAT-PMP for enabling remote access for applications, like games and servers The AirPort Extreme has an audio jack for sending music from a Mac or iOS NAT Port Mapping Protocol - Wikipedia
Sep 29, 2007
Oct 28, 2007 · upnp makes my airport extreme crash with an obscene frequency. As does 5GHz. As does IPV6 tunneling. This thing is mostly a piece of junk, but at least it gets N speeds at 2.4GHz, without crashing