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.
Okay, I’m actually onboard with those things. It’s usually a cable with a single wall plug on one end and four C13 plugs at the other. So you could plug in two monitors, a desktop PC and a printer, say, with just one socket. They’re a lot neater than having a whole power strip and four cables. I’ve also seen ones that split one C14 into four C13s but I’m not as sure how I feel about those.