Q: After updating to 10.7.3 WiFi does not reconnect after waking up from sleep

Hardware problem or not; the issue did not disappear after installing a totally new system (not an update). I still have the same problem, even with only one wifi-station in use. I my case the computer is a 21,5" iMac with the 4-core i7-processor (2,8 Ghz), and the system is 10.7.3. Still: when the computer woke up in the morning, the wifi connection had to be set manually. It finds the signal, ok, but it does not connect to it. But if I shut down the wifi and then put it on again, it connects to the right signal without any problem. But as I said: it has to be done manually! This problem came along with 10.7.3, so probably Apple will do something about it, hopefully very soon.

Vitimtk

Reboot and press option key

Opens startup manager where you can select the required volume to reinstall

All my apps and docs were still there only had to reinstall the printer

This procedure is one workaround for Wi-Fi connection issues after waking from sleep: http://reviews.cnet.com/8301-13727_7-57347274-263/wi-fi-network-not-connecting-a fter-sleep/

It's a little in-depth, but will work to re-establish a connection if there is no Wi-Fi IP configuration after waking from sleep.

Seems to be a workaround that works while we wait for a new update that cures the issue. If one is at least a little bit used to "walk around" in the system files, this will do the job. Thank you, Topher!

Thanks a lot, Topher! Looks like it did the trick!

Here is something I wrote in another thread... I could honestly say I have no problems connecing to wifi when waking the computer. If you go to System Prefences and Network, choose your network; put a check mark in the box that says "Show Wifi status in menu bar," next click the advanced buton, Under Preferred Networks, minus out of all the networks, and put a check mark where it says "remember networks this computer has joined."

It is that simple. If you have trouble, then you just select the wifi symbol that looks like a tornado (that you now have) located next to the time on the menu bar.

I really wish you shared my joy with Lion, because, while I have had minor (fixable) issues that I have accomplished, Lion is really great. And I wish you shared my sentiment or at least tried to utilize 10.7.3 or use recovery assistant to get you back to optimum. The Recovery Disk Assistant is reached by starting the computer from starting the computer and holding down the Command + R keys at the same time, and reinstalling Lion from the server, (not TimeMachine), it could also be found in your utility folder.

Here is my solution, requires no reinstall nor will you lose any of your data/apps:

http://www.24100.net/2012/02/how-to-fix-the-mac-os-x-lion-10-7-3-wifi-network-is sue/

My solution, you will not lose any of your data/ apps. It is also a feature in Lion, please read this link http://www.apple.com/macosx/recovery/ .

When you reinstall lion from recovery lose apps and data? I dont have a copy of time machine.

Fixed the wifi problem?

Immediately after updating to 10.7.3 automatic reconnect to wifi after sleep no longer works.

Did not have this problem prior to the upgrade with 10.7.2.

As per some recommendations I then downloaded and installed the complete 10.7.3 version

and also installed the combo version. None of this cured the problem.

I should clarify that waking the iMac by using the wireless keyboard or magic mouse fails

to reconnect, however, waking the giant by pressing the power button works fine every time.

So it appears that 10.7.3 is a rotten apple and I'm beginning to wonder if Apple's QA group is awake.

iMac 21.5", i5, 12GB, late 2011, Mac OS x Lion 10.7.3 combo

I would suggest if its a big problem to you to roll back  to 10.7.2 via time machine.

Everything will work perfect. This is what i did !!!!  When the problem occured.

Then i tried the cnet article  solution. ...

Hope apple will solve the problem

Vitimtk

I used recovery HD same as you

I didn't notice any issues with wifi during this process

After recovery all my apps documents music etc was still there

All I had to do was reinstall my printer

I am sorry... i replied to the wrong person... I would not even consider rolling back to 10.7.2... that means something was screwy when you upped it in the first place. Just do your best,even if it means using Lion Internet Repair.