Q: Lion WiFi Connection Problem

Strangely, problem resolved itself, hope it does same foe everyone 

I do not have Avast installed on my MB, yet still can't get the Wi-Fi to turn on.  At this point, I've just got my fingers crossed and have made an appointment at the Apple Store.

@jdcliff

I had the same problem, resetting SMC solved it for me.

for SMC reset procedures look here: http://support.apple.com/kb/HT3964

Same problem. I have upgraded 4 laptops and an iMac. 3 of the MacBooks are fine, the iMac is fine but my MacBook pro will not connect. Tried the above fixes - nothing. Hope someone finds the answer.

I've had the same problem since last night.  My issue was resolved following these instructions:

In Network Preferences, turn off Wi-Fi, delete the Wi-Fi service, deleting the Automatic location. Using the + button create Wi-Fi again, and then rejoin the network. Also, under the settings gear icon, choose Set Service Order and move Wi-Fi upwards.

So far, the connection is stable, but this might be a temp fix to the issue.

Cheers

Didn't do it for me - boo hoo.

didn't work for me either using a 2009 macbook pro. my problem is just when waking for sleep it won't connect for 30 secs to a min, which is really annoying because that's just enough time for my time capsule to think i have to wifi and stop backing up so then it has to start all over after i re-connect. it's getting old. Apple, i always upgrade to new OSs the first week they launch since the first OSX and I've had internet connect issues with more than half of them. fix it.

The recommendation to reset the SMC worked great.  Thanks!

http://support.apple.com/kb/HT3964

I have a 2007 iMac and I am having the same problem.  I have tried every posible tip that people have posted and nothing works.  Computer goes to sleep and the wifi goes out.  When I wake the computer, it says it is connected, but there is no acutal connectivity.

i tried it and thought it worked, but it did not. it seems to only not want to connect when i've had my macbook pro asleep for an extended period of time... something like more than 5 minutes. it's weird.

The SMC trick worked for me, but I didn't even have to get that far.

After installing Lion, all of my WiFi devices (iPods, iPhones) would no longer be allowed into my access controlled WiFi network - my desktops are wired to the Airport/Time Capsule via ethernet cable.

I had restarted several times. However, reading the guidance for the SMC reset, it said to restart, the try a _shutdown_ before going to the SMC reset. It was the shutdown that did the trick, which I had not done up to that point.

Thanks, galmeida-us.

JZ

I did the SMC reset, still no result. Any other ideas out there? Same problem - works fine on start-up, but on restart after sleep it doesn't allow network.

Strangely, according to the network utility, it appears to have correctly picked up an IP address from our router at home but still no traffic (either email or internet/browser).

Thanks in advance...

UPDATE on no wifi after sleep issue.

I noticed the following:

1. The MBP does successfully pick up an IP address immediately and appears to be connected.

2. It IS possible to PING other devices on the network. So connectivity is there.

however

3. Even though ping works OK, browsing the internet does not.

Any more ideas anyone?

I installed Lion this morning. I have imac and I have the same connection problem, I did the SMC reset but didn't work. I don't have avast. It's really annoying. I hope it's solves very soon

Same problem here.  WIfi is fine, computer gets put to sleep, and upon waking, connection errors.  But the computer says it's connected to the router.  My fix is to run diagnostics on the connection, which fixes it quickly.  But it's quite annoying.  Everything was fine until the Lion upgrade, so I have to say that it was Lion that caused the problem.