I just bought a wireless card, installed Kubuntu Dapper Drake, and imagine my delight when it just worked, out of the box, no problems at all! Glory be. So I ran a complete update, crowed publically, and went to bed. The next time I started up, the wireless card had apparently evaporated.

The solution is actually pretty simple, but Google is apparently having trouble indexing the Kubuntu forums. Here’s the thread that explained it: “After update no wifi“, and here’s my version of the fix-it-up steps.

First, the symptoms: on a fresh Dapper install the wireless PCI card (mine is an SMC, but it seems the problem is more general) is auto-detected and works. But after running updates and restarting, the Wireless Assistant quits after informing you that you have no wireless devices, and Network Settings doesn’t list a network interface for the card.

Next, the solution: First off, restart the machine but choose an older kernel version. You should have wireless again, and now we’re going to do the upgrade properly, so that you get your updated kernel back.

What’s happened is that the update includes a new kernel version, and the updated kernel module for the wireless card is not in the main repository (presumably it’s non-free or has problematic licensing or something). You need to add the restricted repository to the security updates in /etc/apt/sources.list:

deb http://security.ubuntu.com/ubuntu dapper-security main restricted

(If anyone can tell me the difference between restricted and universe/multiverse I’d be delighted.) Now when you run updates again, you’ll get the module you need. And this is why we started by booting up the older kernel: without wireless you can’t run the update, if (like me) you live on a boat without a cable connection to anywhere. Now restart, and choose the newer kernel, and everything should be golden.

(Incidentally, a tip for the terminally asleep: if you’re living in the Netherlands and getting atrocious download speeds on your updates, it’s worth checking that your repositories begin with nl, not for example au. And if you’ve been downloading from Australia and complaining about the speed of the wireless connection, give yourself a good slapping. I did.

Even better, with the Dapper install CD you could forestall the problem: before starting the install, set up networking. Yes, that means you’ll have to do it twice, but it also means that during installation you’ll have access to the repositories so –presumably– it will choose something sensible. Which is yet another reason for being delighted with the way they’ve handled installation: first run Kubuntu from the CD, then within a working system give you the install app. I guess you’ll probably still have to add the restricted repos by hand though.)