iMac 2011 - no wifi connection after sleep under Lion

Can you believe this. After upgrading to 10.7.4, I am now suddently faced with this too. Never had the problem discussed in this thread. And now, after waking up, my iMac 27 doesn't even see any WiFi networks anymore. Cycling Wifi doesn't help either. Only a full reboot (!!!) brings my Wifi networks back!

Just checked my 'energy' settings and the Mac doesn't even go to sleep. Only the display switches off, but Mac stays on. Still my Wifi disappears. Not sure after how much time.

Anyone else experiencing the same?

I am having this problem as well, It is frustrating that each time I startup or wake I have to select the network manually, which takes a while scanning before showing the available networks.

I strongly suggest to reinstall 10.7.4. Only use the combo update. This solved all my wifi wake, restart and startup connectivity problems.

The 10.7.4 update via Software Updates didn't solve it, but the combo package did. It is available here http://support.apple.com/kb/DL1524

I'm struggling with the same issue with the wifi networks disappearing after sleep. I just installed the combo update, and the issue is stillt here :-(

Problem is now resolved. "All I did" was disabling FileVault.

No clue why disabling FileVault fixed my WiFi but during many many hours on Google I pick up a message of someone who did the same so - desperate as I was, Itried it and it fixed it for me... Vague...

Palantir, may I ask where I can locate FileVault on my iMac as I never used it todate. Thks.

Forget that request Palantir, I located it.

Why and how, however, could that encryption mode affect the WiFi functions ?

Maybe Apple could tell us ?

I made good note of your experience, will try same my end & will let the forum know if it solved my WiFi iMac problem on Lion in so doing.

Cheers !

No luck after all as on my iMac FireVault was never activated, thus my WiFi disconnections cannot be blamed on FireVault.

Never had problems with this.. Last three days I had to restart 12X.. Did the Combo 10.7.4.. Problem is still here, I just put in the cable.. Unbelievable.. Every update is holding your breath..

Serge: Certainly the problem is real. There will be an answer. In the mean time, set sleep to NEVER, and get on with living. If you choose, you might also set " Screen Saver" to never as well- that would save some energy-perhaps more savings than setting sleep to NEVER would add to the power bill.

Nubee, Serge, Palantir and others, there is a mild sense of comfort in reading that one is not alone in facing up to this iMac, under Lion, WiFi disconnection problems.

Until an adequate Apple solution update available I will try "Nubee1" recommendations. Thks all..

Thanks for the advice guys! Putted it to never sleep, hope they wake up @ apple! 😉

I'm running 10.7.4 on a mid 2011 iMac, and the best solution I've come up with is to close mail and firefox programs before I put the computer to sleep or walk away. I wake it up using the power button, and there is a few second delay before the wifi icon shows a connection, but by the time I click to open mail and the browser the wifi connection is up and 98% of the time it all works fine. The remaining 2% is occasionally when I cold start in the morning and the wifi does not immediately connect unless I manually chose my network.

The problem is 802.11d which disables certains channels based on the first beacon the Wi-Fi sees when you wake up the iMac. You need to set the 5GHz channel on your Time Capsule to a channel that is supported in all regulatory domains like 36 or 40.

More info here: http://jeff-with-a-g.blogspot.com.au/2012/04/5ghz-wifi-on-your-mac-got-you-down. html

Hi,

I think I found a solution. To anyone who installed the combo update of 10.7.4:

Yesterday I installed the normal update of 10.7.4 found in this link http://support.apple.com/kb/DL1525

Until now I had no problem connecting to my wifi and backups are going great.

Hope this solves the issue