Airtunes Fuckup

The above error -3256 occurs when IPv6 is set to off shortly after starting playback in iTunes.

If I set IPv6 to automatic it simply times out with no message.

Experiences

While searching for a solution I stumbled upon dozens of users having the same problem. Some could resolve it by:

• Upgrading Firmware to 6.3 (Harrharr, that one's from '2006)
• Downgrading to iTunes 7 (yes, it started with iTunes 8!)
• Disabling Firewall
• Setting custom rules in Firewall (UDP Port 6002)
• Trashing iTunes Preferences
• Resetting and staying with factory defaults

Try #1

• What's working
  • Resetting and staying with factory defaults (meaning, the my iMac joins Airport Express default network, leaving aside my regular network)
  • Setting an Airport Express password
  • Setting an Airtunes password
  • Renaming Airport Express
  • Joining my WLAN
• What breaks it
  • Switching my iMac to a static IP Adress. Using DHCP works. WTF??????????????????????????????????????????????????????ßßßßßßßßßßszszszszszszsz
  • Moving it into the livingroom

Try #2

• What I tried
  • Resetting to factory defaults
  • Setting an Airport Express password
  • Renaming Airport Express
  • Joining my WLAN

FAIL!

Try #3

• What I tried
  • Move in livingroom on higher ground
  • Resetting to factory defaults
  • Setting an Airport Express password
  • Joining my WLAN
  • Powercycling (before I move it again behind my stereo and it fails again, and I frickelout[TM] it from there again...)
  • Moving it behind the stereo

FAIL!

Try #4

• What I tried
  • Move in livingroom on higher ground
  • Resetting to factory defaults
  • Setting an Airport Express password
  • Joining my WLAN

FAIL!

The problem seems intermitting. Maybe it's simply the signal strength? But why-oh-why doesn't it work/fail everytime at the same point? And why does it not work if I move it back near my iMac? Is the signal strength to my WLAN Access point also a problem?

• • Set my WLAN Access Point from Mixed Mode to G. Now Airtunes started working again. WTF?

NO FAIL?

• • Switched to manual IP

STILL NO FAIL?

• • Getting a drink: Aberfeldy
  • Moving it to livingroom on higher ground

STILL NO FAIL?

• • Renaming Airport Express

STILL NO FAIL?

• • Moving it behind stereo

STILL NO FAIL?

• • 01:30am, still workink, Pitr!
  • 7:40am: FAIL!

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Okay. That's it. I'll throw that damn thing outta the window and use good old copper cable.