Why will Airport recognize but not connect to an open wireless network?

May 27, 2009 2:19 PM

Why will Airport recognize an open network but no longer connect to it?

For the past 9 months, I've been connecting to my school's open wireless network with Airport on my Macbook. Last week, my connection dropped and I haven't been able to reconnect since. The network shows up on the Airport menu, but I get a connection timeout when I try to use it. I haven't made any changes or updates lately, so I do not think that is the cause. Airport turns on, and works with all networks but this one. In the advanced preferences section there is nothing under TCP/IP, DNS, or any other tab--although admittedly I have little idea what those numbers mean. I've tried restarting and renewing the DHCP lease, but this hasn't worked. My IT department has given up on the issue (thanks, guys). Any suggestions would be greatly appreciated!

posted by lxs to computers & internet (7 comments total)

Classic symptoms of frequency interference here. Have you tried changing the channel?
posted by fearnothing at 2:21 PM on May 27

I haven't - how do I change it?
posted by lxs at 2:24 PM on May 27

If no other solutions work you could try reverting to a previous Airport firmware version, in case a recent update isn't working well for you: apple support link.
posted by sharkfu at 2:25 PM on May 27

I had this problem with my MBP 17 a few months ago. It would periodically not join my home network and manually connecting would result in a connection timeout. I'd have to sleep it and wake several times before it would connect.

I took it to the Apple store and couldn't reproduce it on their network, and then ran a diag tool that grabbed a bunch of system info/logs and said they'd escalate to one of the engineers and contact me. Never heard from them since. Since then I sold it and bought an MBA and haven't had any issues since.

You could try to console log (Apps->Utilities->Console) for any messages when your connection times out and google them. Also I'd check with your IT department on what type of access point they are using.
posted by wongcorgi at 2:29 PM on May 27

Ah, I missed that it's the school's wireless network, so you won't have access to do so yourself. You could ask one of the network admins to do it for you, they'll know how, but be prepared to be told they have more pressing things to do.

In my experience, Intel macs are significantly more sensitive to interference than most other macs, and most other wireless devices in general. My guess is that the 802.11n standard they use is a tradeoff - they can transfer information faster but at the price of reliability. You could also ask if the school's installed any other wireless technologies recently - like a VOIP system or something.
posted by fearnothing at 2:33 PM on May 27

I've had some weirdness with an Intel Mac's wireless, too. I don't remember where I got this advice but I wrote down in a text file and it sometimes seems to help:

Go to the HD/Library/Preferences/SystemConfiguration. Trash the com.apple.airport.preferences.plist and NetworkInterfaces.plist. This will require your password. Restart your computer.

You may have to rejoin wireless networks and re-enter any wireless passwords. My wireless problems seem to end up being the computer self assigns an IP address instead of getting one via DHCP. So I don't know if this will help you but it's worth trying. You don't even have to trash those files, just stick them on your desktop and restart. You can always restore them to folder if it doesn't help.
posted by 6550 at 3:08 PM on May 27 [2 favorites]

That's what it looks like if I try to connect to my wireless router with a new computer, like if a visitor brings theirs for a few days. It's because I have the router doing MAC address filtering, with only my computers white listed. Even without a password enabled on the network, it will fail to connect with no explanation until I add the new machine's MAC address to the whitelist.

If the IT guys can't figure it out, it probably isn't that.
posted by ctmf at 6:10 PM on May 27