Given the 2.5Gb port also supports PoE in, I think the idea is that you can plug this into a 2.5Gb PoE port on a seperate managed switch and that's the only connection you need; that's certainly how I would use it. WAN connections could be plugged into that switch, along with the APs, user devices, servers, etc, with them seperated using VLANs. Assuming everything was gigabit except for that 2.5Gb link to the OpenWRT Thing™, you'd be hard-pressed to saturate that 2.5Gb port and you'd still have the gigabit port completely free for... whatever.