We began to track reports of Wi-Fi disconnection issues back when we upgraded one of our iMacs to a brand new 2011 model and started to experience daily Wi-Fi signal drop-offs—across-the-board disconnections of everything from iChat to Twitter and Safari. It wasn’t an isolated issue: plenty of people on Apple’s Discussion Forums were having the same problem, and hoping that 10.6.8 would fix it. When that didn’t happen, the hopes shifted to Lion. UPDATED: Originally posted on July 21, 2011, this article has been updated with the latest information from Apple as of February, 2012.
Now that Lion’s out, it’s clear that the problem wasn’t fixed—it’s actually become even worse on our iMac, which has started to lose its Wi-Fi connection multiple times a day. The same problem is being reported by numerous Apple Discussions users, in threads such as Wifi Constantly Dropping in Lion, Wifi Problems After Installing Lion, Lion WiFi Connection Problem, and New MacBook Pro 2011 weak and dropping wireless connection.
Based on testing, we get the impression that the issues stem (at least in part) from some mismatched or messed up settings saved by the Mac relating to specific wireless networks it has connected to before.
Some people believe that there are wireless network settings with incorrect disk permissions; others think that there are corrupted files. Solutions that have been offered include:
(1) Deleting a system preferences file called com.apple.aif.plist, then restarting the machine to rebuild it. This is inside Macintosh HD > Library > Preferences, which is now harder to find in Lion’s Finder because Apple has hidden your hard drive by default in the Sidebar’s list of Devices. You can use Finder’s Preferences to add Hard Drives back to the Sidebar, but based on our experiences, deleting this file doesn’t work to fix the problem.
(2) Reset your Mac’s PRAM and NVAM. This was suggested by an Apple Discussions user, and is explained in this Apple Knowledgebase document. Most reports do not suggest that this works.
(3) Reset your Mac’s System Management Controller Another suggestion from an Apple Discussions user, explained here. Again, most reports do not suggest that this works.
Based on past experiences in trying to fix major issues such as this one, we know that it’s rare that one solution works for everyone, and that readers often come up with great ideas for how to get things working again. We’re going to keep hunting for answers to this, and will update this article when we have one that works for us—did one of these ideas, or something else, work for you? Post in the comments section below.
Updated September 8, 2011: After trying many different fixes, none of which worked for any extended period of time, we tested something new. After changing the passwords on both of our wireless networks, then setting the iMac up with the new passwords, the disconnect issue appeared to go away. Hopefully this or one of the other solutions recommended below will help you.
Updated February 22, 2012: Users—including one of our editors—have continued to experience problems at least intermittently despite several point releases of OS X 10.7, and Apple has posted an updated solutions page here.