I had this problem, working in an office, updating one iMac, not another.
I believe this may be linked to differences between US & EU/ROW wireless - where US hardware doesn't see channels 12 & 13. My suspicion is that Apple updated their software to match the lowest common denominator (ie. the US wifi settings) without telling everyone.
After the OS update, I couldn't see my nice, healthy wireless network - though the other macs were still accessing it happily. I changed the wireless broadcast channel from 13 to 11 and low and behold - it worked. There are so many networks here that I had to muck about a bit to find a new channel without interference (ie. lots of Airport drop-outs) and eventually settled on channel 1.
Working cheerfully now, I just hate Apple a little bit more today than I did yesterday.
I've spend quite some time trying everything suggested in this thread.
The only thing that actually seemed to eradicate the problem was removing the network from the "Preferred Networks".
Then again, 10.6.8 causes different problems for different people/macs.
Only time will tell what you have to do... [scary music]
This worked for me..!!!
After scraching my head for 2 days this is a life saver..
My wife's new(ish) MacBook Air had the same problem. As soon as she upgraded to 10.6.7, she lost internet connection - though wifi signal was still strong. We were hoping the new upgrade to 10.6.8 would fix the problem. It didn't. I tried everything - PRAM, disk permission repairs, etc etc. Finally, this evening, on a whim, I decided to input my old DNS settings (from when I was using the Witopia VPN) into her network settings. I have no idea why, but her connection returned immediately. I tried deleting them again to make sure it really was that, and the connection was lost. Put them back, and the internet came back. Bizarre. We are not even using Witopia anymore (we are in China, and use Asterill). Can anyone explain what's happening?
I have the same issue as well on my mini's airport interface. i had no issues with connecting to internet over wifi until i upgraded to 10.6.8. Now, i have issues connecting to the wifi, intermittent connection and very slow speed even if i get hooked up.
I tried all the techniques laid out in this thread -
- Deleting the plist file in Library-->Preferences
- Installing the 10.6.8 combo rev 1.1
Nothing is helping.
Instead of waiting for another update or a rev 1.2, i have decided to go back to the original snow leapord version that is available on my DVD. Hopefully that should fix the issue.
There are many factors that can come into play here. The 10.6.8 update MAY introduce some changes that make the airport card in the Mac more sensitive and this means it may pick up additional routers from other networks (networks you do not plan to connect to) versus what it did before the update. From a computer that is successfully online, you can run iStumbler to survey the routers in your neighborhood. When I did this I found several from other houses down the street that were broadcasting very strong signals. They were on the same channel my own router was on. First, I deleted the existing Location and created a new one. I then had to re-enter the router name and password. Then I went into the more advanced settings for that Location and removed all other networks from the list and told it to only connect to my preferred router. (Leave in names of routers you may connect to at other times, however, such as when you transport your Mac to another physical location.)
I believe that this effectively screened out the other routers whose signals were competing with mine. In fact in one location in a far corner of our house, the neighbor's router is actually stronger than my own, and this was preventing my Mac from consistently staying with my router. After the above changes, it now stays on the proper router, even when its signal is weaker than the others.
From reading the posts, it sounds like while my suggestion may solve SOME of the problems, others have to do with other factors (such as U.S. versus non-U.S. hardware).
This problem goes back to 10.6.5. This solution from tenortim fixed my and others wireless connection problem after upgrading:
Say thank you tenortim.
I've had this issue for the last couple of days, and being a new to the world of macs, I struggled somewhat.
However, I run VirusBarrier and noticed that it had blocked a couple of blocked IP addresses, both of which were from the network.
I cleared these from the list, and bingo, my iMac is now successfully staying connected to the internet.
Hope this helps
Not sure if people are still having issues with new install of 10.6.8 causing wifi to drop out all the time on the iMac. Just spent half a day pulling my hair out and on the phone to Apple. Tried almost everything suggested in the threads - reinstalled 10.6.3 and Safari worked like old - but Mail went belly up. Updated to the 10.6.8 Combo - and Mail worked and Safari went belly up and network was dropping again.
I talked the Apple guy out of a HD wipe - and tried some mroe suggestions here. It is obviously 10.6.8 talking to the wifi - as I have my MBP on the desk next to the iMac and it is fine.
Final fix (so far.... ) for me was deleting my wifi network from the network preferences (Turned Airport off / System Preferences / network / find your network name and delete) - then turned airport on and set the network up again.
Still slightly slow - but it works.
Hope this helps somebody as it seems there are lots of frustrated users. Apple guy "hadnt heard" of other people with the same issue. Here's to the power of collective intelligence - not the textbook...