Airport Extreme and error -6753 or -6742
Prolem: after firmware upgrade, you cannot connect via airprot utility to the airport.
When doing so you get error -6753 or -6742.
Complate firmware reset:
remove power for 30sec, and then reconnect power, press reset botton for +10 seconds.
Then when done, and all is complately reset, set up the airport again to your needs.
Only apple can anwser, my guess: pure bad design and imcompance from Apple.