Mountain Lion no Wifi after wake from sleep

Hello NKDO, to manually put iMac to sleep, is it still working fine so far?

Yes, I have to turn off energy savings.... and manually hit the apple/sleep everytime I am going to leave for a while. Or just shut it down.

It is a shame that the Sleep does not work.

Someone at Apple gotta have this laptop and have this problem daily, or not??

I didn't catch your problem, your laptop loose connectivity when you wake it up, or during sleep?

Mine is, after 4-6 hours of sleep, my iMac disconnect from the network. So I can't perform wake on lan...

With all the various symptoms and conflicting resolutions in this thread, I think you've hit upon a key: the network's advertised country code. Interestingly, this is also a rather esoteric setting that might explain some of the randomness of people's experiences in this thread.

Earlier in this thread, I posted my symptoms for the Mountain Lion operating system not finding its WiFi network when waking from sleep. I tried many of the solutions posted (ditching cached copies of network associations, eliminating certain applications like Parallels) to no avail.

The first relief I had was when I first stopped my hard drive from sleeping. This improved matters greatly but did not solve the problem. I went from multiple freezes a week to infrequent freezes about once every 2nd week. Still painful but much better than before.

Watching this thread, I noticed your post about the country code. Looking at my Airport's configuration, I can only see how to set the country code for the Airport's 5GHz network (which I had not been using).

I configured and named my Airport's 5GHz network (ensuring the country code was set to U.S.) and set my Mac to connect to the 5GHz network by default. I have not had a freeze in over 6 weeks.

"I configured and named my Airport's 5GHz network (ensuring the country code was set to U.S.) and set my Mac to connect to the 5GHz network by default. I have not had a freeze in over 6 weeks."

Now, do we know this is an issue with other access points? How do we change those settings?

Ever since I entered the command

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist

then

sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist

I've had problems with WiFi not staying connected. Very frustrating. I have a MBP 13" 2010, 10.8.2 and FIOS. I never had a problem before entering those commands.

I had this same issue after upgrading to ML. I read all the boards and tried all the tweaks. Finally gave in and went to Genius Bar. While they were working on my issue (they hadn't heard this issue happening) I found another board with a solution, showed the genius and he was just about to try this. Turns out so far so good.

1)Delete Contents in /Library/Preferences/SystemConfiguration and /Library/Caches

2)Shutdown computer, turn off main power to mac and leave for 15secs

3)Turn on the main power

4)Power on mac and do a PRAM reset (Press and hold the Command-Option-P-R keys). Wait for 2 audible beeps then let go of keys

5)Test and verify if issue resolved.

In my case the issue was still but less frequently popping up. Moreover, the performances were very bad for wifi bandwidth.

My solution was to acquire a wifi extender that also act as a bridge between exact wifi protocol, ... But didn't force me to reconfigure anything on the existing router. Only drawback of the extender was the impossibility to configure MAC address filtering security on top of WPA2.

This works! I had cleaned out the /Library/Preferences/SystemConfiguration files before but not the /Library/Caches. The laptop sat all night and when I went to it this morning it was still connected. Great advice! : )

After installing 10.8.2, my MBP doesnt connect to wifi after waking up. There doesnt seem to be consistent solution to this problem. Can someone explain if this is a known problem? If yes, what is the resolution?

I have the same problem here: no internet connection after wake up from sleep although Wi-Fi is connected to the network.

I am using Time Capsule configured in bridge mode.

I have tried all suggestions here in this thread but no luck at all. Not even a hard resetting my MBP or reseting PRAM solved the problem. Sometimes the internet connection goes back after 5~10 minutes after waking up, but the most of the time I need to restart Time Capsule in order to get Internet back.

Important to say that even if there are other Wi-Fi networks avaiable although I am able to connect to them the result is the same: no internet connection regardless which network I am connected to.

This is extremely annoying and Apple seems to do absolutely nothing about. I am really considering returning my new hardware.

My configs are:

MBP Retina 15"

OSX Mountain Lion 10.8.2

Time Capsule

I don't think there is a universal solution. There are so many varibales involved. For example cleaning out the cache worked for me, but it created another problem. I use Verzon FIOS and when now sometimes when a call comes in it knocks me off the network and takes a few minutes to search for the WiFi signal before reconnecting. I know this is probably a Verizon problem but who knows it could be a router configuration issue that is intereacting with TCP/IP protocal stack on my MacBook.

I'm sure Apple must have support engineers monitiroing this site, but it would be really helpful if they can offer solutions when it's related to the users configuration (as opposed to a software bug that Apple has to correct)

Does anyone have any clue on whats wrong with the ML OS and not re-connecting to wifi after waking up?

Well, I have been talking to Apple Suport and It is unsure if this is a hardware or a software problem, but after I have tried about everything suggested in this forum, finally adding openDNS IPs in my wi-fi connection instead of using the one my ISP provides worked for me.

Here is how to give it a try:

Go to System Preferences, Network

Click on Advanced and then on DNS

Click on the + sign and add 208.67.222.222 and then click + again and add 208.67.220.220 (check out these openDNS IPS here http://www.opendns.com/business-solutions/premium-dns/benefits/)

click OK

click on the lock to prevent any modifications (optional)

click apply

Restart your Mac.

Since then it has been 1 week without any lost connection after waking up my MBP Retina,

People should give it a try.

Message was edited by: leandro_br

I had the same problem after upgrading and tried every solution I read. Finally I went wired, then assigned a static IP to the computer on the router. So far it has worked - I have restarted a few times and it has reconnected after waking.