I recently upgraded my router (TP-Link TL-WR1043N) so now my wireless network is broadcasting in 11b/g/n mixed mode, and my 1st generation AirPort Express is having trouble joining the network.
I have done a factory reset several times, and each time everything seems to work fine but then when the APE tries to reset, AirPort Utility bombs with the message
AirPort Utility was unable to find your AirPort wireless device after restarting.
I'd love to keep this working just as an AirPlay device.
UPDATE: I tried resetting the wireless network to use 11bg mode, but got the same result. So I'm guessing the thing has just crapped out coincidentally at the same time I made the change to my network. Oh well!