Q: iMAC 21" WIFI failing after 10.7.4 update

Kirill -

Please verify that you took the steps listed in your message and this stopped the wifi drops.  Thanks.

Phil

+1 for restoring IO80211Family.kext 4.1.2. In detail, what I did:

1) Make a backup or copy /System/Library/Extensions/IO80211Family.kext to a safe location.

2) Delete /System/Library/Extensions/IO80211Family.kext (the version in OS X 10.7.4 is 4.2).

3) In the Finder, open /System/Library/Extensions, then enter Time Machine.

4) Go back in time until you find IO80211Family.kext 4.1.2.

5) Restore that file.

6) Restart immediately.

The above assumes that you are on OS X 10.7.4 and you have a Time Machine backup of a previous version of the OS (otherwise, you must get IO80211Family.kext from somewhere else, like an installation DVD). I didn't delete cache files or perform other steps more than the above. Step 2) is necessary because Time Machine would not overwrite the original file correctly, apparently due to some locked files.

I have tried all the other proposed solutions in this thread—except changing the authentication method from WAP2 Personal to something else—and none worked. For me, this is definitely an iMac-specific bug in that kext.

For the record, the problem (disconnecting wifi, no network visible any more, restart required) occurred with an iMac connected to an Airport Extreme. Other devices on the same network (MacBook with OS X 10.7.4, iPad) have always worked fine.

That fix was given to me by Apple Care via phone.  In worked for a very short time.  Now the wifi drops are back consistently and  persistently.

Kirill -

I changed from WPA to WPA2.  My wifi connection has been on for the past 10-15 minutes with no drops.  But I've had other periods of stability followed by a continuation of the drop problem following fixes by Apple.  So I'll wait on this one but keep you posted if the problem recurs.

philkds,

What router make and model are you using ?

My router is a Belkin G Plus MIMO Model No. F5D9230-4

It's worked for my current iMac 11,1 for 2 years prior to problems associated with the 10.7.4 update.  There were no prior issues.

The Belkin has also worked with a MacBook, MacBook Pro, iPhone, and HP Windows laptop with no performance issues.

FYI when I was at the Apple Store for the wifi drop problem the techs suggested I use WEP.  They said is more secure than WPA.

The connection was stable for an hour.  Then it dropped.  So the problem is still present.  I had this experience with a fix by Apple Care that involved deleting the SystemConfiguration file and rebooting.  Things looked stable for a brief period and then reverted to the dropped signal mode.

That router has pretty bad reviews:

http://www.amazon.com/Belkin-F5D9230-4-Wireless-G-Plus-Router/dp/B000E5BKP0

Have you tried any other router ? Is your drafter 11n certified ? ( It should say it on the box). If it's a 2+ year old router, they used to sell these pre 11n certified routers. Have you checked if there's a firmware upgrade available for this router...

Just listin a few things in case any of them helps your case.

deleted the connection and restarted the router

thanks!

anybody tried G only mode and no encryption ?

I think we need to be careful here... there are obviously a number of issues. The one that I think we are all focusing on is the problem effecting the iMac 2011 (possibly a few other models) with the 10.7.4. patch applied. This is a driver bug that can be fixed with a downgrade to the 10.7.3 driver. These instructions are included in the thread. Some of the other topics discussed are whilst worthwhile appear to be related to earlier problems. It appears based on this thread and others that the only solutions, that work consistently, are

1. Disabling bluetooth (far from ideal)
2. Moving to a cabled solution
3. Appliying the 10.7.3. driver
4. Apple fixing the issue.

Oddly enough I think number 4 is the least likely at present since there appears to be a complete denial the problems exisits (Not unusual).

The list is helpful. 

My experience is somewhat different from some of the others.  I have a 2010 iMac model 11,1.  10 days ago I updated from 10.6.8 to 10.7.4.  At that point the wifi drops started.

Regarding applying the 10.73. driver, my iMac was at the Apple store for 3 days of testing.  They could not replicate the drop problem.  They requested and I provided permission to do an archive of my files and reinstall of the OS.  Upon returning home I discovered that they had done a reinstall of 10.7.3.  The wifi drop problem was still present.  So in my case the 10.7.3 driver did not address the problem.

An Apple engineer contacted me via email last night.  He said he would like to help debug the wifi drop issues I've experienced.  He asked me to provide him information about my setup.  He also asked me to run several commands and provide him the output.  I sent him the info tonight.  Will share any useful info he may provide.

I had seen a suggestion in this forum about changing to WPA2.  I changed my router from WPA to WPA2.  I was able to get a wireless connection whereas I had none with WPA. 

But I don't consider the problem solved.  Since May 12 I've had intermittent ability to connect wirelessly using WPA.  The occurrence and duration of disconnects seems random.  So I'm not convinced the connection problem has been resolved by changing to WPA2 although I've got my fingers crossed that it does.