Q: iMac drops Wifi connection after 10.7.4 update

After a day and a half of trying to get Mountain Lion to download (WIFI droped every 15 minutes or so) and install, it seems the problem no longer exists.  I'm not 100% sure yet, but it seems to have been addressed in ML.

I can report that after suffering this problem with the update to 10.7.4, that I seem now to have a stable wi-fi connection on my 27" iMac.  In my case the solution (as has been mentioned by one or two others in this thread) was to set up my Airport Extreme with separate names for the 2.4GHz and 5GHz radio networks and then select the 5GHz network on my iMac (and in fact I removed from the iMac any reference to the 2.4GHz network).  I still left the channels to be set automatically on the Airport Extreme. This has now been stable for some weeks.  The 2.4GHz channels are very full (I live in the UK and houses are close together), but there is nothing but my airport extreme on 5GHz.  This also seems consistent with the experience of Allison Sheridan and her husband (see http://www.podfeet.com/wordpress/2012/05/365-imac-wifi-istumbler-diskinventoryx- alarmed-clear-shure-se535-headset-apple-security/),

I'm not sure what to recommend if you don't have the ability to set up a 5GHz network.

I am new to this forum but am having the same problem with my wi-fi netwrok connection.  I have read all the posts and tried all the suggested remedies, but nothing has helped.  My network drops evey 10 minutes or so, and sometimes when I turn wi-fi off and on, it will reconnect,  but sometimes it won't even recognize my router.  I ended up going into the router - Netgear - and set the security from WAP2 to "none" (but of course I don't want to leave it this way) and the problem seems to have gone away.  Does this make sense to anyone?

Your experience has a familiar ring.  In my case I changed a Belkin router from WEB to WPA2.  This eliminated 85-90% of the drops.  There are still intermittment drops after sleep.  Since you read through the posts, you've seen that this issue problem has numerous variations and possible solutions.  But so far Apple has not been able to provide one overriding solution.  It's been reported to occur in ML as well as 10.7.4.

I don't know whether or not this might be the case for you guys, but after installing that kernel extension from the Dutch website (link below), the problem disappeared. However, the problem returns if a program called InsomniaX is open. This program disables the computer's sleep option, allowing processes to run with the lid closed. As long as this program is open, the problem will contnue. If the program is closed and the computer rebooted, everything is back to normal (providing the kext is installed).

http://www.appletips.nl/os-x-10-7-4-fix-voor-draadloos-netwerk-problemen-imac/

(Google Translate that to English).

wow! I thought I was alone, I thought my imac was getting old or was in need of repair.............I even changed operation systems..........I just went to lion  10.8.1  and it just did the same thing,,,,,,,,this is crazy. je

I just did what you suggested and I'm not sure long term what it will do, but my internet is way faster and not as sluggish..........thanks!

The biggest problem is apple has not acknowledged the problem. Their solution with me was to replace my network card (lucky it was under warranty) but of corse, this dit not work. I suggest everyone keep calling apple and refer them to this and the many other threads...check google. I am very hesitant to upgrade to ML untill apple at least acknowledges the problem and says ML is the fix. I think I will be waiting till **** freezes over before apple actually admits a problem with ANY of their products.

Daryl, don't be reluctant to upgrade to ML. Many of us had the problem solved with the upgrade. After you upgrade you might have to fiddle with your sharing preferences (changing the security to WPA2 Personal). I have had 0 problems after the upgrade.

I had the same problem.  Frustrating to no end.  Wifi in/out randomly very frequently.  Multiple calls to support center.  No resolution.  I was using a netgear N600 dual band router.  Finally decided to try an AirPort Extreme.  Plug in the Airport, no issues what so ever.  Wifi works flawlessly.  I don't know why this is and I don't care.  All I know is that my wifi works great, my wife is no longer giving grief and all is good in the neighboorhood.

Just my $0.02.

JP

Could this finally be the answer?

The 10.7.5 update also includes fixes that:

• Improve Wi-Fi reliability for iMac (Late 2009 and newer)

Well, the 10.7.5 update took care of my problem too.  Now I have diddly squat for wi-fi.  My imac can't even find my wi-fi connection (it says "no hardware installed"), much less drop it.  When I go to the network assistant, it can't find my router either.  I know the router is still working because my wife's windows machine is working fine (and it's further away from the router) I have taken a giant technological leap backwards and have hard wired my computer to my wireless router so I can post this p*&^%-off reply. 

Great, any ideas now??

Can't wait for 10.7.6

I updated to 10.7.5 so I have my fingers crossed that this will fix it. I am happy that Apple has acknowledged there is a problem. I too have a Netgear n600 router which works perfectly with all my other wireless devices.  The problem I think a lot of people are having is that we will try something and it does "fix" it for a period of time but then the drop signals will return. Also I Think it is highly unlikely it could be our routers because when the signal is dropped we cannot detect ANY network. I can see at least 10 other wireless connections when things are working okay but then when the signal drops all of the other SSIDs also drop. The fault must lie with the internal wireless card and  its software drivers.

I have had wifi dropping earlier, but once i have done the following as mentioned in the link below, I have now resolved the wifi issue

https://discussions.apple.com/message/19630352#19630352

I restored my imac to 10.7.4 from time machine and my backup disk and now my imac recognizes wi-fi (whether it will drop wi-fi connection or not remains to be seen)  So, my "no hardware installed" under 10.7.5 is definitely a software problem, not a hardware problem.

I guess I'll wait for 10.7.6 - oh joy!

more on this story later