With the advent of Airport Express Firmware Version 6.3 which facilitates for multiple speaker play, life got simpler and a little more complicated all at the same time.
If you’ve not altered your Mac OS X 10.4’s default firewall settings then you most likely will not be reading this article. However, if you have utilised the advanced features of the firewall then here’s the solution why your AirTunes is refusing to work.
You may experience a -3256 error message whilst trying to engage the multiple speaker mode:
The solution is simple. The ‘Block UDP Traffic’ option must be disengaged under the Advanced feature of your Mac OS X firewall which can be found within the Sharing pane of your System Preferences.
Once that’s done, the multiple speaker function should be working like a beeze once again. If you’ve not adjusted the firewall settings from its default factory settings then you shouldn’t have any issues, since Blocking UDP Traffic is set to off as default.