Q: Internet connection lost after sleep - Ethernet

my wife's imac (2010) started losing it's internet connection after it was asleep.  This has been happening all of a sudden this past 7-10 days.   The time capsule is only 3 feet away.  My macbook air in the same room has not ever experienced this problem.   I was thinking of taking it into the apple store, but kinda of a hassle packing it up.   I guess I'll wait the next few days and follow this forum to see if there is a fix.

Try waking it by pressing the power button (instead of a key or the mouse). That works on my iMac (OS X 10.7.3 Lion). Several people on these discussion boards have had success with this approach, when the problem has been with a wifi connection. This thread seems to include both wifi issues and ethernet issues.

Of course, something is still very wrong and this seems to be a relatively new problem for at least some of us. When the iMac fails to connect to the wifi router after sleep, the problem (for me) is not the ISP, or the router, which are all working fine. The iMac simply fails to connect to the router and obtain a DHCP address.

Not being an engineer, I have no idea what the difference is between waking up by pressing the power button vs. a key or the mouse, but there's got to be a clue there somewhere.

My wife recently purchase iMac, OS X ver. 10.7.3 with Airport Extreme. It connects the Mac and PC and iPad. Only the Mac loses connectivity after sleep. After inquiring about it with Apple support we were told there is a bug and Apple is working on it. How long they working on it, who knows, but at least they are aware of this defficiency. Re-booting the Mac restores connectivity till next sleep.

Turning the power off with the power botton is not a safe practice.

Waking by pressing the power buttom is no help for my lost-connection during sleep problem. It makes no difference at all.

I do not use nor have Airport Extreme nor do I have a Time Capsule yet I have had a problem with my internet connection after sleep. 

I did get rid of my Mac Magic Mouse which was also giving me a lot of "lost connection" problems and went with a wired mouse.  So far I have not had any problems with the internet connection after sleep.  It has been one month.

I've had it with OS X updates.  Same loss of WIFI after sleep or off here.  Time machine also sometimes takes hours rather than moments.  Pain in the neck. Applecare said the issue is being addressed.  Let's see... Problematic on my Late 2009 iMac and on my Early 2011 MBP.  I DO use Airport Extreme.

My imac 27" (OS X version 10.7.3) loses wireless connection with my airport on sleep ever since an airport update about 2 weeks ago.

That's it-It was the Airport Update

Went to Apple store Genius Bar in Scottsdale yesterday and these guys just heard of this!  They had 3 imacs in yesterday.  They don't know anything about it and basically said that something like this "should" be corrected soon in a new operating system release.

I can only hope so!  Everytime I come out of sleep mode on my new imac I have to manually reconnect to my wifi.  Tried a lot of things and nothing works.  If anyone knows of a fix PLEASE let me know!  This is very annoying and I cannot believe that Apple hasn't addressed it yet!

LOL, Same old Apple Store associate script- they NEVER have heard of anything!!! Except it IS a known issue at AppleCare.

For four days now my iMac has connected perfectly to the internet upon awakening. Has anyone else had the experience of this annoying problem suddenly vanishing?

I didn't update any program(s) four days ago, as far as I know, and I have no idea what else might have changed.

Of course, now that I've posted this, I suppose the problem will be back in the morning....

There was an update a few days ago. My iMac does not have a problem either now that the update went through. Looks like it's been fixed.

I did the software update for my Late 2009 iMac related to losing WIFI and an Airport Extreme firmware update and so far, all seems well.

I wish there were some way to have an on-line party!

Note that the first post in this thread was back in 2009, but you all know the cliche.

I did the update but still losing internet after sleep.  I am using ethernet and not wifi so this fix did nothing for me.