Reset PMU/SMC/NVRAM for AirPort card power issues [Useful for: Built-in AirPort hardware not recognized]

Some data suggests that a power-related issue may be at play in the issue of AirPort cards not being recognized.

In these cases, resetting your Mac's power management unit (PMU) for PowerPC-based Macs or system management controller (SMC) for Intel-based Macs may be helpful.

Instructions for resetting the PMU for various PowerPC-based Mac models are contained in the following Knowledge Base articles:

1. Mac Mini
2. PowerBook and iBook
3. Power Mac G5

Instructions for resetting the SMC for various Intel-based Mac models are contained in the following Knowledge Base articles:

• Mac Pro
• MacBook and MacBook Pro
• iMac and Mac mini

Resetting NVRAM may also resolve some AirPort-related power issues.

In order to perform this process, shut down your Mac, then start it back up while immediately holding the following keys: Command, Option, P and R. Hold the keys down until the computer restarts and you hear the startup sound for the third time.

Turning AirPort card off then on [Useful for: no Internet access, cannot connect to router]

You may want to try turning your internal AirPort card off then back on if you are having access issues. This can be accomplished through the AirPort menu item, or using Internet Connect (located in the Applications folder)

Check for/quit third-party wireless applications (monitors/sniffers) [Useful for: slow wireless throughput, repeated dropouts]

Some third-party applications that manipulate or otherwise interact with the wireless connection may cause problems -- particularly an issue where speed vacillates quickly between normal and dismal throughput.

Among the implicated applications are older versions of coconutWiFi.coconutWiFi is an application displays you a small aqua-bubble at the top of your screen which indicates whether or not. you're in range of a wireless network. Current versions of the application do not exhibit this bug.

Reverting to older AirPort kernel extensions [Useful for: slow wireless throughput, router not recognized]

f you are experiencing dire AirPort connectivity issues after a major system update (incremental Mac OS X update or Security Update), and have exhausted all other workarounds, you can try reverting to older version of the AirPort kernel extension via the following steps: [WARNING: This workaround is risky because you should not generally mix and match kernel extensions after updates. You will also lose any AirPort-related refinements brought about by the most recent update and new conflicts can ensue. Still, in a bind, it can restore wireless connectivity where other workarounds fail.]

1. Download the Mac OS X combo updater directly precedent to your current system version if you applied an incremental Mac OS X update (e.g. Mac OS X 10.4.9), or your current system version if you applied a security update from Apple's download page.
2. Download and install the shareware application Pacifist
3. Drag the Mac OS X combo installer package (e.g. MacOSXUpd10.4.9Intel.pkg) onto the Pacifist application icon.
4. Click the triangle next to System to expand it
5. Click the triangle next to Library to expand it
6. Click the triangle next to Extensions to expand it
7. Scroll down and find the file AppleAirPort.kext. Drag it to your Desktop or another location (you will have to enter your administrator password)
8. On your Mac OS X startup drive, navigate to /System/Library/Extensions and locate a similarly named file (AppleAirPort.kext). Move it to another location for safe keeping.
9. Now drag the file from step 7 (the one that you retrieved from the Mac OS X combo install package) into the /System/Library/Extensions directory on your startup, in effect replacing the newer file (installed by the AirPort updater) with and older copy -- you will have to enter an administrator password.
10. Restart your Mac

Remove kernel extensions (Mac OS X 10.3.9) [Useful for: slow wireless throughput, router not recognized]

If you are running Mac OS X 10.3.9 and are experiencing this issue, navigate to /System/Library/Extensions and drag the following files (if they exist) to the Desktop or another location outside the System folder:

• AppleAirport2.kext
• AppleAirportFW.kext

Restart your Mac and check for restoration of AirPort connectivity

"Keep Looking for recent networks" [Useful for: router not recognized]

In some cases, selecting "Keep looking for recent networks" in the Network pane of System Preferences can resolve an inability to connect to local networks.

Delete then re-establish wireless network [Useful for: system will not automatically re-connect to network after sleep]

You may need to delete then re-establish any encrypted AirPort network configurations in order to take advantage of automatic reconnection capabilities after sleep or restart.

Move SystemConfiguration folder [Useful for: weak reception]

Moving the folder SystemConfiguration located in /Library/Preferences, to the Desktop then restarting can resolve some connectivity issues. This workaround appears to be effective because of permissions problems that can affect the SystemConfiguration folder, and the therein contained com.apple.airport.preferences.plist file. Note that this workaround will require you to re-enter network configuration settings and may cause other lapses in functionality.

Turn on Interference robustness [Useful for: weak reception, slow wireless throughput]

Try turning on the Interference robustness option -- accessible in the AirPort menubar item, or by selecting "AirPort" from the Network pane of System Preferences then clicking "Options..."

Delete specific .plist files [Useful for: System will not automatically reconnect to network after sleep, slow wireless throughput, cannot connect to router]

Try deleting the following files from the ~/Library/Preferences/ directory (this is the Library directory within your User folder):

• com.apple.internetconfig.plist
• com.apple.internetconfigpriv.plist
• com.apple.internetconnect.plist

In addition, delete any other files that have are named as such: com.apple.internetconfig[...]

Also, try deleting:

/Users/username/Library/Application Support/Apple/Airport/