Thanks for your reply.
How could it be a hardware/firmware problem if it worked before?
It seems to be a problem on Lion's side, or with iTunes. Do you think updating to Mountain Lion would help?
I just submitted the bug to Apple, here's what I said:
Summary:
I have been using AirPlay with my AirPort Express G (802.11g) for many months without any problems in Lion. After the recent iTunes update, it no longer works (errors 15006 and 6753).
I have tried solving in numerous ways (see below).
Steps to Reproduce & Expected Results:
Connect to AirPlay speakers in latest Lion iTunes with AirPort Express G.
Actual Results:
When I try to select the AirPlay speakers in iTunes, it shows this message for a long time: "Connecting to "AirPort"..."
And then this: "An unknown error (-15006) occurred while connecting to the AirPlay device “AirPort”."
After that, the option to play from the AirPlay speakers disappears in iTunes. And I can no longer access the AirPort Extress via the AirPort Utility (5.6).
Regression:
I have to reset it, and start over. However, that doesn't work either.
I have tried:
- disconnecting the AirPort from the power,
- factory resetting it countless times,
- restarting my MacBook Pro (SSD),
- installing AirPort firmware,
- changing IPv6 settings for WiFi,
- using ethernet cable, and without.
Now, I also cannot set up the AirPort properly anymore. In AirPort Utility, I get the error (-6753). After that, it does seem to have been added. But when I try the AirPlay again, it has the problems as above.