Ask Max: Mac will not reconnect to the wireless network after sleep
I have several Apple computers connected to a new Airport Extreme N in my home. All work very well and connectibility is never a problem, with one exception. I have an older eMac (1.00 GHz G4) that will not automatically join the network after it sleeps. I have set it to join auto and "join a specific network", but it still is lazy when it wakes up and I need to click and join.
I know this is no big problem, but it is frustrating when my wife calls (often) and complains that "the printer is broken" or "we don't have the internet in the front room anymore." Do you get my problem? Help please!
A few things may be causing your eMac to forget what wireless network to join. The fist place to look is within your password keychain. In your Utilities folder is an application called Keychain Access.app that will allow you to view, edit, or delete your saved passwords. Search for "AirPort" in the search box located in the upper right hand corner of the Keychain Access window. Delete all entries you find for AirPort. Now when you try to connect to the network, you should be prompted to enter your password. Enter it and save it to the keychain. Test the eMac to see if it reconnects to your wireless network after sleeping.
If that doesn't work, you can try deleting two preference files. One is found here: /Library/Preferences/SystemConfiguration/com.apple.airport.preferences.plist and the other is here: /Library/Preferences/com.apple.networkConfig.plist. Once you have placed those two files in the trash you will have to restart. After the eMac is running again, go to the Network System Preference and re-enable Airport.
Hopefully one of those two things should work for you and stop the tech support calls.