WiFi disappears after 10.7.5 update on iMac

Question

I posted this in the iMac drops wi-fi connection after 10.7.4 update, but it occurs to me that this might be a different problem.  I was having problems with my wifi dropping connection under 10.7.4 just like most of the people in the other thread.  I tried all of the "fixes" suggested, but nothing worked.  Then apple came out with the 10.7.5 update with claims that it would improve wifi reliability, so I installed the update and my wifi disappeared entirely.  I could not turn it on from system configuration, and when I clicked on the wifi icon, it read "no hardware installed".  The only way I could connect to my "wireless" router was to install a wire!
Luckily, I have a back up drive so I reinstalled 10.7.4, and my wireless network (and those of my neighbors) reappeared under the wifi icon.  I don't know if I will have the same disconnecting problems as before because I'm going to leave the cable installed until apple figures this whole mess out.  One giant technological leap backwards!
Anyone else had this experience?
Maybe 10.7.6 will fix it ???

Answer 1

Hey there. I had the same issue as soon as I updated to 10.7.5 (Lion) on Friday morning. After spending countless hours troubleshooting my router and my MacBook Air, talking to Apple Care, visiting the Genius at the store and searching the forums/net for an answer, I got the issue fixed. I also use a Netgear router and there are a couple of issues with the update, one being that it doesn't work with the old Netgear firmware.  Here's a complete step-by-step on how to get it resolved. My internet is working flawless now for a few hours and faster than before.
1. Update Netgear Firmware: If you can't of course do this from your laptop, try another device (phone, iPad, tablet, etc...).
Enable the Wi-Fi, connect to the router, and go to:
http://192.168.1.1  Type in username: admin password: password
Should automatically tell you there is a new software update. If not, go to Router Upgrade.
2. Go to Wireless Settings (in Netgear): --> CHANGE CHANNEL to 3 or 9. --> CHANCE SECURITY to WPA2-PSK [AES]
3. Let it refresh. (Wi-Fi goes offline and then back on).
4. Go to Network Preferences on the MacBook (or laptop device) ---> Advanced --> and delete your router from the preferred list.
5. Go to Macintosh HD (hard drive) --> LIBRARY --> PREFERENCES --> SYSTEM CONFIGURATION --> and under developer, DELETE the following three (3) files:
com.apple.airport.preferences.plist
com.apple.network.identification.plist
NetworkInterfaces.plist
6. RESTART the computer.
7. Go to Network Preferences: At the top, click on LOCATIONS and add a new one. Call it whatever you want. Then make sure when you are done, that it is now working off the NEW location.
8. At the left, you see the pane that has the Wi-Fi or Bluetooth or whatever device listed. Click on the gear at the bottom --> SET SERVICE ORDER.  Again, make sure the Location is the new one you just created. Choose Wi-Fi.
9. Connect to your router: Make sure you are using the NEW location.
10. RESTART computer.
Check and make sure you are connected. If you aren't connected, let me know.
Just an FYI:
If you call Apple Care (whether you are in warranty or not) let the first POC (verification department) know you are calling about a software update issue. They will transfer you to tech support. Once they transfer you, tell the tech specialist you want to be transferred to the Wi-Fi specialists. Yes, they actually have a team of Wi-Fi specialists!!
Most of the steps I got from reading the Apple forums here. The only thing I didn't see anywhere was to change the channel to 9. She said it might get busy so remember the channel setting process and change to 3 or vice versa.
Don't listen to any of these that say download this patch or revert to 10.7.4, etc... Just keep 10.7.5 and do these things.
Hope it helps! Let me know