iMac 2011 - no wifi connection after sleep under Lion

Upgraded my 21.5" I5 Imac, to 10.7.1, and this absolutely did NOT, fix the problem. At first it seemed to resolve the issue, ... but that was a fluke. The thing comes out of sleep mode and still has issues with WIFI. Airport says its connected, but from an Internet perspective, Nobody Home.. I just turn off Airport and turn back on, and this resolves my issue. Evidently 10.7.1 was addressing more pressing issues... so maybe in 10.7.2?

Same problem here with Lion on my 2007 24" iMac. 😟 Using a Time Capsule wireless router, but doubting that is the problem.

I am having the same problem on my new iMac running Lion. I did the upgrade to 10.7.1 and the problem still exists. Everytime it goes to sleep I have to turn off wireless and then turn it back on to have it work. It shows connected but nothing happens. I'm really surprised and disappointed they haven't fixed this yet.

Yep same here!! No problems in SL 10.6.8. Now on L 10.7.1-WiFi is a non workable feature in Lion...Apple really needs to get it together.

Mid 2010 iMac 27" 3.2GHz i3

I am not having problems since downloading the latest update on 8/21! 😀

I am experiencing the same problem in the "lastest and greatest from Lion" where my iMac does not want to autoconnect to my WiFi network after going to sleep. It requires me to pick my network to connect. Works fine from that point but no one should have to be asked to join a known network that is already set up.

This guy has 3 possible solutions but I did not try any cause I am new to the Mac settings, hence don't know where they are - which keys exactly or that HD location to remove such file.

http://reviews.cnet.com/8301-13727_7-20095988-263/fix-wi-fi-autoconnect-problems -in-lion/?tag=mncol;title

Same problem for me on my mid 2011 MacBook Pro. After upgrade to lion constant disconnects on the wireless 802.11n (5 ghz) network coming off an Airport Extreme. To fix I would right-click the wireless icon, turn wireless off, then turn it back on. Would work just fine for about 5-10 minutes then do it all over again. More a bother than anything else. The update on Monday seems to have fixed the problem (at least most of the time).

No problem with wired access - never had the problem with Snow Kitty. Seems we have a Stack problem Apple needs to really address a fix for in the next software update (HINT HINT!!!).

I've done the same way.

I've moved the iMac to near where the router is.

So I connected it via a cable.

The wired connection is more reliable and faster and give a room for other devices to connect to the wifi better.

An update for my iMac not wanting to automactically stay connected to wifi after going to sleep.

1) I turned wifi off then on again

2) Went into advance settings and removed the Apple store wifi info leaving only my username wifi.

My wifi now stays connected after going to sleep and does not require me to choose a network listed in the pop up box.

Same problem on a late 2008 macbook, need to reboot after sleep to get wifi.

OK folks - some more seasoning for the soup here. After fiddling with this and that on my WiFi setup I noticed that, while the Airport Extreme was pumping out both 2.4 and 5 Ghz versions of my WiFi network the Airport Express downstairs was only expanding the 2.4 GHz version - opposite what I wanted. I cleaned up the setup and made sure all were on the same wagon and am now getting a much stronger signal throughout. It remains to be seen if I still have the constant disconnects. But something tells me I may have "stumbled" on to the root of my problem.

Mid 2011 Apple iMac 27" i7 and Mid 2011 (new model) MacBook Pro 15"

Network made up of a DLink 2640B Modem/4 Port Router and WAP (WAP function disabled), a Version 4 Apple Airport Extreme pumping out a 5 GHz 802.11n wireless network, with an Airport Express downstairs being used to expand the wireless network on the far side of the house.

I had 2 wireless router, one is Aztech wireless G and other is Belkin wireless N. But this problem only happens to me when connected to Belkin -> sleep MBP -> and unable to connect back. everytime after MBP sleep, I have to enter my wireless N password, then it always say invalid, but then it connect successfully. it doesn't occur if i connected to any wireless G based router. hope apple release the fix soon for OSX Lion. This is really frustrating..

Been a while since I updated on this ribbonbut I finally have the fixes I needed. As far as Safari opening pages slowlywhen using a hard wired connection Apple finally came up with the fix. Turns outthe DNS Prefetch often asks for more then your provider allows. The quick fix,and believe me it works, is to turn off Prefetch using Terminal. Open Terminaland type in “defaults write com.apple.safari WebKitDNSPrefetchingEnabled-boolean false” then hit enter. Clean out youcache, close Safari then open it again. Should have no problems after that.