Airplay works from iOS but not OS X

[Undecided]

Hi. Why would Airplay work from my iOS devices but not my Macs, when there's a third party wireless AP in between?

If everything goes through my Apple Time Capsule, no problem.

If there is a third party access point in between, the Macs can see the airport express but when trying to use its speakers, it just fails to connect. So, I guess I'm also asking, why would a Mac be able to see an Airport express (in iTunes) but not be able to play through it?

The AP has no filters, firewalls, or anything. I just can't figure it out. Anyone hear of this before?

[Undecided]

It's a distinct pattern that shortly after I post a question, I find the solution.

Never mind - it's an IPv6 problem with Apple. Turning off IPv6 (on the Macs, not router) solved the problem. (Though, it may work to turn if off at the router level.)

See this thread.