[POST Final Update (Feb 07, 2012): The solution with the Combo update has improved the situation, but about 25% of wake-ups will still be disconnected. Before 10.7.3, I’ve never had that issue.]
[Final Update: The issue seems resolved. Repairing file permissions and rebooting once more after the combo update seems to have healed my mac. It stays connected now.]
I should have known it: never install updates before they are at least two weeks old. I’ve never had any problems with my WLAN connection on Wake-Up before I installed today’s Lion 10.7.3 update. Ironically, Apple’s support document says:
- Resolve a Wi-Fi connection issue when waking from sleep
In my case, the update did quite the opposite: every time my iMac went to sleep and wakes up again, I have to connect to the WiFi manually.
[Update: AppleCare told my to install the combo update on top, but it didn’t help: When the iMac wakes up, the WIFI-indicator in the menu bar shows that the system is looking for networks, but it doesn’t connect, even though the network it was previously connected to is listed as available. Clicking on the network then connects nicely.]
[Update 2: At least I am not alone: https://discussions.apple.com/message/17477940#17477940. It seems for some people the combo update has helped.]
Thank you, Apple! I’ve re-learned something…