I connected an Ethernet cable to my AirPort Express, and to the Mac Mini, then ran the Network Setup Assistant - System Prefs.> Network > Assist Me > Assistant. The Mini didn't connect to my network. I unplugged the Ethernet cable, and ran the Network Setup Assistant again, and while I was doing so, the Mini connected automatically.Evidently, the mere act of plugging and unplugging the Ethernet cable was enough to refresh the whole thing.When I plugged it in, the Mini saw a "new" network and tried to connect to it. For whatever reason it didn't, but when I unplugged the cable, the Airport Express "refreshed" the IP address, and the Mini went back into 'wireless search mode'. It found my network, connected to it automatically, then I was able to open Safari and start downloading por ... ahem, I mean, um, reading poetry blogs.