iMAC 21" WIFI failing after 10.7.4 update

There ya go - http://support.apple.com/kb/TS4209

Hi Kirill and Glasscut, I have MCS index 0 and I am experiencing this problem even I have the last software installed. That proposed patch was released in february and from time to time (last occurence was last week) I am still having this problem. Somebody have contacted me from Apple Support and suggested local technician discussion but no one called me back. I hope Mountain Lion will be the solution.

Hi!

MCS index 0 means:

In other words:maximum speed on 20mhz can be 7.20 and maximum speed on 40mhz 15 mb/s.

It is very very slow.which router do you have?

Try this things:

1)wep2+AES

2)n and g/n mode (try both of them)

3)change the channel to 1,6 or 11

Hi Kirill, today, it happened again. I woke up the iMac from sleep and after a couple minutes, wifi was gone. I am using Apple Airport Extreme in 802.11n mode, channel 100 (DFS, 5 GHz), WPA2 personal, speed 360, MCS index 0, RSSI: -42. It is displayed when pressing Option key and clicking to Wi-Fi icon in the menu bar.

But now, after several attempts it says MCS index 0, RSSI -51, speed 450. It seems RSSI and speed is changing, the other remains the same.

Update: while typing this, the wifi drops twice and I need to reboot everytime.

speed 450 and MCS 0..hmmm,sounds more than strange.try to use G only mode.dont use N mode,let's see what will happend

I don't know if this applies to anyone else, but I noticed that I have no problems with Wi-Fi connection when I'm alone at home. When my wife comes home, I constantly lose it. Then after testing a few things, I realized that I only lose my connection when she uses her phone (which happens to be an android). She also uses her Macbook air but there seems to be no problems with that. No problems with my iPhone and the iPad either. When she uses her Android phone is when the Wifi issues spring up - on the iMac, macbook, iPhone, and iPad.

This isn't so much of a fix but just something I came across.

ha ha ha, I am at the same point. In my case I thought my neighbour is the root cause of the wifi drop. Until today again it was worst case scenario. Wifi dropped continously. But when I am using the Airbook, the airbook wifi works fine. This is really very strange.

I have tried to switch off all other equipments but still the Mac's wifi connection goes crazy.

I belive also the problem came with an update one or two month ago.

I am worry to crash the Mac performance when I would try to revert the installation.

Sorry not be able to come up with a solution just don't wast your time on tracing after your wifes phone as problem cause.

Also hope to get a solution presented I can manage. Cheers

Same issue here with MacBook (Early 2008). Its really annoying to the core. I am having to reboot very often. Sometimes even the reboot does not work. The same issue happened a while back but apple did fix it with an update. Hope this will get the priority.

I tried everything except deinstalling the patches. I'm praying that a clean installation of Mountain Lion will fix the issue or I'll have to buy a Wifi USB Stick.

Anyone installed Mountion Lion? Wifi issues solved?

I too have had all the well documented wifi issues on my mac, tried everything 40 times over to no avail. I installed Mountain Lion a few hours ago and am happy to report that the wifi has yet to drop! Hopefully I didn't just jinx myself.........

Good news. . .so far!

Same here. Installed Mountain Lion a few hours ago and everything is working great.

Since the installation routine (clean install) I can't add a wifi network conenction. In the settings I'm just not offered Wifi. I tried booting the recovery partition but there it still says "no Wfi hardware installed". Ican't remember what Wifi data the system profiler showed in Lion, but now I just see software details, no hardware. Does anybody have an idea how to start the Wifi? It worked before and bluetooth still works so I'm not sure if it's a hardware problem.

And this works for me: changed the router chanel from 9 to 11 and wireless mode setting to 802.11 n/g/b mode.

The Mac then automaticaly chose 802.11n mode. This setting works so far well. Testing it with listening to www live radio. No interruption so far.

My old "problem" setting was:

Hope this works for you too. Best regards Markus