I was going to spin a long-winded tale, but I'll just get to the point...
My deuced Mac(hina) was having problems connecting to my AirPort Express Base Station after restarting, and, ultimately, AirPlay stopped working and AirPort Utility was unable to deal with either of my two Base Stations (for different reasons, no less), although I still had wi-fi internet.
A fortuitous shut down/start up cured all ills.
Good old,
basic troubleshooting still works!
