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I just updated my Ubuntu 12.10 today and it went fine and I was told to restart system and after I restart my WiFi stopped working. Mine is Broadcom BCM4312 card . It was working fine just before the update, I tried reinstalling driver from software sources and it didn’t work, it shows the proprietary driver in use but network manager doesn’t detect my WiFi card.

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I cant answer it my reputation is too low to answer the question before eight hour. This link might help others with bcm43 series cards – Rohith Raveendran Oct 24 '12 at 14:36
up vote 12 down vote accepted

I just fixed the issue, I found the kernel sources has not been installed which prevented from compiling the driver properly. So I installed kernel source for the current kernel from Synaptic then issued the following commands and my WiFi was instantly restored (like 3 or 5 seconds).

To install kernel headers and source:

 sudo apt-get install linux linux-headers-generic kernel-package

 sudo apt-get purge b43-fwcutter firmware-b43-installer firmware-b43-lpphy-installer firmware-b43legacy-installer bcmwl*

 sudo apt-get install b43-fwcutter firmware-b43-lpphy-installer bcmwl*

Then reboot.

This applies to BCM4312 only (My laptop is Lenovo g450)

For others can see this blog post, this might be useful for you.

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I too had faced this issue. I connected it to wired lan and I again ran apt-get upgrade and restarted, then it started working.

I feel this is the worst installation upgrade from Ubuntu.

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Indeed it does :( – faken Oct 25 '12 at 22:16

Check /etc/resolv.conf I was also facing the same issue as loopback address was there as my DNS preference. If this is the case, then correct the dns address to resolve issue.

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Go to Dash -> Software Sources -> Additional Drivers -> Using Broadcom 802.11 Linux ...

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sudo apt-get install bcmwl-kernel-source

I had same problem, with this everything will be fine.

If didn't install try first:

sudo apt-get remove bcmwl-kernel-source
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protected by Community Feb 23 '13 at 4:32

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