I live in a building that has wireless internet. How do I use it while also having access to my wifi network, which connects my Mac to my other devices (Philips Hue, Belkin Wemo, streaming music from my Mac to my Apple TV, etc).
I'm using the latest version of macOS/OSX on a Mac Mini, plus an iPhone and an iPad. I also own an Apple Airport Extreme, which I'm using to serve my local wifi network. I also have a 1st gen Airport Express that I haven't used in ages, but it's old enough that the OSX Airport Utility app can't configure it (I think it's from 2006?).
UPDATE: I answered my own question. See answer below (tl;dr: I bought a new Airport Express & added it to my setup)