iMac 2011 - no wifi connection after sleep under Lion

"I am experiencing the same issue with my 27" iMac after upgrading to Lion. With Snow Lepoard I did not have an wireless issue, but now whenever I wake the compter, I have to mess with the network settings for up to 5 minutes just to get it to reconnect."

Same issue. I go to network diagnostics to get my 2010 iMac to connect. It had no problems connecting before Lion. None of my other devices have any issues connecting to the router and getting an internet connection.

Hi I am having the same problem with my 27" iMac but on Snow Lepoard. This has happened since the latest software update. I dont have a problem with my 2007 20" iMac running on SL which has had all of the same updates.

Add me to the list of folks with this problem. 27" iMac running Lion 10.7.2. I've tried nearly everything in this forum as a solution with no success. I've even swapped out routers, changing brands from Netgear to Linksys.

This problem began when I upgraded to Lion. Prior to that, there was no issue at all with WiFi. I would go wired, but the location makes it difficult. This is a simple problem to recreate, all you have to do is tell the iMac to go to sleep, then wake it up. After that, no WiFi.

PROBLEM: Loss of WiFi connection when computer sleeps.

SOLUTION: Workaround - Using airport dropdown on main menu bar, select network. Connection is reestablished.

DETAILS: iMac 27" intel, approximately 3 months old. No sleep/reconnect issue prior to upgrade to Lion. Older WiFi iMac in same location has no problem immediately reestablishing connection upon wake, Leopard is the operating system for that Mac.

RECREATE PROBLEM: Apple->Sleep. Allow computer to sleep. Wake Mac. Connection lost.

Well, on Friday I contacted Apple. The guy at the end of the phone (in the US) seemed very confident that he knew about this being a problem and a simple fix was avilable. He would be able to do it over the phone if I took out a one-off applecare support case for £35 or pay £135 for three years.

I asked was his fix guaranteed and he said yes as he knew what the problem was. He then gave me the option of going to my local Apple shop and have it fixed FOC and it would take 15 - 20mins to do.

I took my Mac to the local store. They did not know of the problem or of any fix. Various tests done and no fault found.

My mac connected over and over agin in the store. They suggested I reload my OS.

Since I have brought it home I have altered the setting on my TC to 802.11n only (5Ghz) instead of 2.4Ghz and it now works a treat although a little bit slower on download speeds.

Hi, just wanted to let you know, what has worked for me, or at least seems to be working. Although I did check remember joined network and remember this network, I was stuck with a problem. My mac, after waking up, was trying to connect to wifi, but did not succeeded. When I manually selected the very same network it asked for password. The same story everytime.

I then went to delete all my locations, hit assist me -> assistant and created a new location. I chose the network, entered password....and ta daa. It works 🙂 Im not sure if you need to delete all your locations as the assistant did not create the new location anyway. Hope it helps.

Cheers

Luke

I have a mid-2008 27" iMac (now obviously out of warranty, although I still have 90-day support for Lion) with an original Time Capsule, one Wi-Fi network only, which has *always* wakened for network access, as I have been syncing from my 2011MBP - also on Lion - several times daily for most of this period. With Lion, it refuses to wake for network access. Although I do have ethernet access (NOT at the top of the network list) I have not bothered to try it, because its use is not practical for me.

This is beyond frustrating. My sync program will not work unless the iMac responds. It is located over 100' from the Mac, which means I have to either leave it running permanently (via Caffein only - did not seem to help through System Preferences - Energy Saver) and I'm not even positive that did it 100% of the time. While I believe it did, I laerned that it overrode my Energy Saver settings, causing my display to remain on - or to come on when it woke for network, and then remain on. Tried using the power button, but the problem was not solved (can't recall precisely what happened.) Both computers are running the latest update of Lion.

I also use dynDNS and can no longer "Connect to Server" (server = iMac). I have *never* had these problems, and am frustrated beyond belief. I'm not willing to try anything "technical", as I am the opposite of computer literate. That includes not letting tech support talk me into a disaster, particularly having seen how many others are experiencing this problem.

I had the same issues with my iMac 21.5" Mid 2011 after upgrading to Lion. Symptoms were slow to connect or no connection to Wi-Fi after sleep without cycling Wi-Fi off/on. I also had random disconnects - but maybe they are not related as they were fairly rare. Anyway, I figured I would be patient and wait for software updates to fix the problem, but after two LION updates and no fix, I decided to contact Apple. I used the "Express Lane" - "Call Me Now" feature and within 10 minutes I was talking with a real person. I thought this was great and I congratulate Apple on such speedy service.

NOTE: The process to fix the issue requires you to delete your Wi-Fi networks and set them up again. So passwords need to be handy. Also I am writing this from quickly scribbled notes while on the phone and my memory, and the fix may be very specific to your Mac, so use this info I provide here at your own risk. By using this process you agree to not hold me liable for any issues or problems you incur. It really is best for you to talk with Apple support if you can.

Process:

Remove your Wi-Fi networks.

1. Open “System Preferences” (Dock icon with gears) navigate to "Network"
2. Highlight "Wi-Fi" in left pane and then click on "Advanced..." in main window. (you may need to unlock the padlock to make changes)
3. In "Preferred Networks" window, highlight then remove your network(s) by clicking the minus button. When done click "OK" then "Apply"

Delete Keychain files

1. In Applications/Utilities open "Keychain Access" program
2. In left pane under “Category” highlight “Passwords”
3. In main window Delete all entries of kind: “AirPort network password” (using Kind to sort them makes it easy)
4. In left pane (upper) in “Keychains” pane highlight “System”. This most likely will be locked. To unlock, click large lock just above left pane and enter your system password.
5. In main window again, Delete all entries of kind: “AirPort network password”
6. Relock your System keychain. Close window.

Rebuild the System Configuration Folder

1. In “Finder” navigate to Macintosh HD (your hard drive), then navigate to “Library” then “Preferences” folder.
2. Drag and copy the “SystemConfiguration” folder to your desktop.
3. Close out everything and restart your computer.
4. Once back up and running you need to setup your networks again. Let AirPort detect them and then re-enter your password(s).
5. That’s it.

I have not had a lot of time with my iMac since the fix. But normally I would have had a connectivity problem by now. Hopefully this permanently fixes this very annoying issue. Good luck all.

-Will

Unfortunately, it didn't work on my 27" iMac. I followed all of the instructions, connected to the WiFi, then put the machine to sleep, then woke it up. No WiFi connection.

I have had loads of problems with this. However the apple support team assure me it's a known problem and are working on a fix to released very soon.

this is actually normal, the reason your connection drops when your mac goes in sleep modus is because your imac will try and save power and use the minimum requirement of energy , yes even your internet will be shutdown to save energy , now you can always undo this setup in system preferences.

- the reason your network location needs to be reset is kinda odd though.

- system preferences - > network -> try making a new location , add a new wifi after adding the wifi -> set service order <- ( the symbol next the the - minus ) -> place the newly created wifi at top service , apply settings

see if your newly created wifi network needs to be reset each time the mac sleeps.

The trouble is it wont connect to wifi after being woken up and attempts to connect to a fictious ip address despite saying it is connected to mine. only turning it off and then on starts it up. As I said apple know it is a problem with Lion.

Add me to the list people. I have a 2011 macbook pro recently purchased a month ago. It didn't do it at first but now its the worst. I am about to convert back to PC!

I have a brand new 27" 2011 imac that started having issues like this a month or so back. I have always had issues where my mac (previously a mini) and xbox would drop signal simultanously, forcing a reset of the router. but on this one, like every one else it became every time i brought it back from sleep. One small difference however, I always had internet connection for about 5 minutes or so, after wake, and then it would cut off. No other computer or devices were affected. after reading a few threads on here and hearing what some people thought was the issue, i decided to try one unproven solution, cuz it seemed way easier.
THE SOLUTION: simply download and install google chrome. it has worked like a charm for three days now, not a single hiccup. the suggestor proposed that the issue was (paraphrasing and not quite sure im using correct terminology) that the protocol for internet in safari (apple based) and protocol for the rest of the system (UNIX based) were conflicting. by golly it worked. even with keeping safari open along with google. the problem was reliable as gravity before, now its non existant. another solution that worked for a few people was to restart, then restart again and hold down command+contol+ another button (sorry) that would reset wifi or something or other to factory default.

hope it works for you guys.

😀

Tried Will's suggestion and it worked! Although I didn't have any of the "airport network files" so I don't think it was anything to do with that.

I moved the Preferences file as suggested (and I also ejected an SD card that had been sat there since before the problem started, just in case).

Just to note though, I had been putting off the latest Lion update for ages simply because it required a restart and I couldn't be bothered. Finally got round to it yesterday and that's when the trouble started. It must have been something to do with that??

Thanks a lot though, much appreciated. I'm new to Mac and I'm loving the helpful forums - saves a lot of time and money!! =oD

I went to the genius bar today and all my hardware checked out. The guy seemed to think its a router probelm and suggested I reset my router, which I am reluctant to do at the moment because it will probably crash. So I will try Will's idea. I still think it's a Lion problem which Apple have pretty much admitted. I just hope the fix is released soon.