Q: iMac 2011 - no wifi connection after sleep under Lion

You made my day!!!!! Is there a way I can kiss your butt?

Thanks a lot!!!!

I got something to work.

I changed the setting in my router to only allow MAC address connections. Disable any passcode secuirty and only allow the MAC address you manually add to connect to your router. That seemed to work for me, and the connections are always more stable this way as well.

Try this:

 

System Preferences > Network > WiFi > Advanced > TCP/IP tab: Configure IPv6 "Link-local only".

 

After trying numerous other fixes, this appears to have solved the problem for me. Since changing IPv6 to "Link-local only" Lion has never failed to reconnect after waking from sleep.

This one worked for me, thanks !!

Hello,

I was having an issue with my 1-month old MacBook Air -- not with inconsistent wi-fi -- but with having to reconnect to any (both at work and at home) wireless network upon waking from sleep (e.g. opening the lid after going to and from work). It was getting to be more of a PITA more than anything, so my searches brought me here.

Here's what worked for me:

I followed someone's suggestion to set the following:

System Preferences > Network > WiFi > Advanced > TCP/IP tab: Configure IPv6 "Link-local only"

This alone did not work but after doing the above AND also clearing out all my preferred networks via the following:

System Preferences > Network > WiFi > Advanced > select ALL preferred networks and click "-"

Did my issue clear up.

Upon waking my mba from sleep, it now auto-connects to my wireless network (after I selected it the first time).

SUCESS!

This is perhaps my third posting to this discussion.  Mine is a mid-2008 iMac.

I have continued to try each and every solution suggested here as they have appeared.  Nothing has solved the problem, even momentarily.

My iMac is also now working correctly after the "Link-local only" and deleting preferred networks.

After all the problems I had with my iMac, Apple replaced it. At first it seemed to be fine but the problem hasn't gone away. Apple said if the replacement failed to work it was probably my router, but I think this is incorrect because everything else works with my router.

It has to be Lion that is the problem. I just hope that OSX 10.7.3 resolves this wifi conection problem. I hope that it is released soon as the problem is driving me nuts.

cheers

I have seen the same issues on my Mac Pro as well, for me it is not a major issue and doesn't require much but waiting a few minutes to let it reconnect to my Belkin Router. One thing I would say is, **do not ever remove or delete system files or folders as someone posted**. Apple would never tell anyone over the phone to do this. Good practice is to wait for Apple to address the issue if it is affecting as many people as it seems to be. They will usually put out a software update. Good luck to all.

As I was still having problems I looked around the other routers in the area and they were all using channel 1 ,6,or 11 which seems to be the standard default setting that the automatic selection uses.

So I changed mine to channel 13, which my router warned me that some devices won't like it. However I went with it because the mac works with channel 13. Since then I have had no problem and in fact the connection seems better! I will still keep my fingers crossed as I don't want to speak too soon.

Anyway perhaps if you are suffering this problem then it might be worth a try.

cheers

I was having basically the same problem with my brand new, out of the box 27″ Quad-Core 2.7GHz last night.  It detected my wireless network immediately, but if I tried to use my iPad on the network or another machine (like my older 20″ iMac) it would boot the new machine off the wireless.  All other devices continue to work flawlessly.  The older iMac has 10.4.11 and has never had any issues with our wireless network. Also the new 27″ iMac would occasionally drop the wireless connection even if no other devices were using the the network.  The only way to reconnect was to turn off the wireless setting, and then turn it back on.  I spent 3 hours on the phone with Apple support, going through literally 3 levels of their tech assistance trying everything and nothing worked.  Finally I was transferred to a supervisor who suggested I trash my system configuration folder and reboot.  That seemed to fix the problem.  The guy was puzzled as to why a new, just out of the box machine would have a corrupted folder, but it did seem to stabilize the wi-fi connectivity for me.

I was concered about deleting what seemed to be a very important file (with all it's contents), but the wizard at Apple support assured me that the system creates a new one at boot if it doesn't find one in existence (which it did). 

Worth a try.

*UPDATE*

So, 24 hours after deleting the system config folder the problem came back.  My solution was just to forgoe the wi-fi connection and run a ethernet cable from my router to the iMac (which works flawlessly).  My conclusion is that there is some problem in these newer machines in how they handle wi-fi that Apple is unwilling to acknowledge.

The latest update to Lion mentions a fix for the WiFi sleep issue.  I intend to install it tonight and see.

In the meantime, I've simply left my computer on and had the screen turn off.  That works, and while you'd think it would shorten the life of the computer, I'm not 100% certain.  Those heating and cooling cycles can sometimes be worse than running it at a stable temperature.

If anyone has success with the update fixing this problem, be sure to post here.

After installing 10.7.3 my problem is worse then ever.  Before it was sporadic with it connecting most of the  time when it woke with sleep and only occasionally failing.  Now it never connects and I have to manually connect every time.  Heck of a fix they made.

I upgraded to 10.7.3 this morning and my 21.5" Mid-2011 iMac has still lost connection, but now it immediately reconnects and then sends a report to Apple. It happened less today than typical. It usually drops WiFi connection with out coming back online unless I turn AirPort on and off. Usually about 6-10 times a day, the most happening after the display comes back from sleep *note: i don't have my mac go to sleep, just the display*. Today it happened twice, but again I waited about 5 seconds and it immediately came back online. I don't know if others are seeing any difference with the update, but I am.

Hope it gets better Louiskst and everyone!

I had fixed my wifi issues in the systems preferences although it does not work for everyone.

I updated Lion the other night and now my mac doesn't stay connected to wifi after I put it to sleep and get back on. I have to manually go into wifi and find my network.

Come on Apple...