Why doesn't Airport reconnect after sleep or shutdown?

Question

I have a MacBook Pro (2.4 GHz Core 2 Duo, running OS X 10.6.8) that does not reconnect to its stored WiFi network after it restarts or goes to sleep. To reconnect, I need to go into System Preferences and choose a network in Airport settings. Then it happily reconnects and stays connected.

I saw this question, and tried to delete and re-add my preferred network (I only have one). I went into Advanced, deleted the network, turned Airport off and on, and chose my network from the dropdown. It knew the password already though.

I was going to delete/move the preferences file containing network/WiFi settings, but I can't find it. Would this be helpful? If so, where is that file stored? I've already looked through ~/Library/Preferences and /Library/Preferences to no avail.

Answer 1

The problem got partially better on its own, and it's not clear why. There were also a lot of old networks in the list of previous wifi networks in System Preferences, and it helped to delete them.

The complete fix, however, ended up being to go into the list of wireless networks (in System Preferences > Networks > Airport, Advanced) and move the desired network up to the top of the list so it was joined first. There was one called "linksys" on top that was matching a neighbor's network, and then failing to get internet access for some reason; I think it was added a long time ago for a different network of the same name.

I thought I had tried this before, but either something changed or I didn't actually try it. I'm asking this question to help me troubleshoot someone else's computer, so I'm not aware of everything that might have changed since I originally posted the question.

Answer 2

There is one famous cause of this problem - interference between bluetooth and wifi, which plagues metal Mac laptops.

To test if this is the source of your problems, turn off your Bluetooth via System Preferences / Bluetooth and see if the issue goes away.

If this is indeed the problem, the only cure (as far as I know) is to stop using Bluetooth entirely, or switch the frequency of your wireless setup to 5GHz.

Answer 3

The preferences files you probably want to look at are:

• /Library/Preferences/SystemConfiguration/com.apple.network.identification.plist
• /Library/Preferences/SystemConfiguration/com.apple.airport.preferences.plist
• ~/Library/Preferences/com.apple.eap.profiles.plist

As @gentmatt said, you could also try deleting the network password from your Keychain (use Keychain Access.app).

Answer 4

This is also a very common side effect of the WiFi network password changing but using the same SSID.

The old password gets stored in the Keychain, and does not get overwritten. Or two entries for the same SSID are in Keychain.

Once you go into Keychain Access.app, look for 'airport network password'.

If it is your WiFi network to control and nothing else works, try a new unique SSID and password.

Answer 5

Does this happen to all networks or just the one you're talking about?

If the latter, is your box a Netgear OEM (given out free by networks?) I have one in my house from Virgin Media which rejects my 2010 pro (same spec as yours) from automatically joining, and the way I solved it was asking them for a wireless access point box (very cheap, even if you have to buy it) and wiring that into my network. It joined immediately, and had no problems.

I also considered the possibility that there might be interference on the same channel as our network - we're in a very high-density area, so that might be causing the problem.