Wi-Fi Update for iMac sleep issue: Time to wake up
As is often the case, Apple has identified a problem and then followed that up with a solution. Specifically, late 2009 and newer iMacs running OS X 10.7.3 are having trouble connecting to Wi-Fi after waking from sleep — here’s their fix.
Apple defines the issue in OS X Lion: iMac may not automatically reconnect to Wi-Fi network after waking from sleep, an informative if wordily named knowledge base article.
After waking an iMac running OS X Lion v10.7.3 from sleep, the computer may not automatically reconnect to the Wi-Fi network it was associated with prior to sleep.