Comment 4 for bug 1818134

I had a look at my Updates history in Ubuntu Software Centre for the last couple of weeks to see if I could spot any "likely culprits", and I see that on the 18th February the 'dkms' package got bumped from 2.2.0.3-1.1ubuntu5.14.04.9 to 2.2.0.3-1.1ubuntu5.14.04.10 and the 'shim-signed' package got bumped from 1.33.1~14.0.4.3+13-0ubuntu2 to 1.33.1~14.0.4.4+13-0ubuntu2

I found https://askubuntu.com/questions/138284/how-to-downgrade-a-package-via-apt-get and 'apt-cache policy dkms' tells me that only versions 2.2.0.3-1.1ubuntu5.14.04.10 , 2.2.0.3-1.1ubuntu5.14.04.5 and 2.2.0.3-1.1ubuntu5 are available (not 2.2.0.3-1.1ubuntu5.14.04.9), so I tried 'sudo aptitude install dkms=2.2.0.3-1.1ubuntu5.14.04.5` and got the following output:

The following packages will be DOWNGRADED:
  dkms
0 packages upgraded, 0 newly installed, 1 downgraded, 0 to remove and 0 not upgraded.
Need to get 65.4 kB of archives. After unpacking 3,072 B will be freed.
The following packages have unmet dependencies:
 shim-signed : Breaks: dkms (< 2.2.0.3-1.1ubuntu5.14.04.10) but 2.2.0.3-1.1ubuntu5.14.04.5 is to be installed.
The following actions will resolve these dependencies:

     Remove the following packages:
1) shim-signed

Accept this solution? [Y/n/q/?]
The following packages will be DOWNGRADED:
  dkms
The following packages will be REMOVED:
  shim{u} shim-signed{a}
0 packages upgraded, 0 newly installed, 1 downgraded, 2 to remove and 0 not upgraded.
Need to get 65.4 kB of archives. After unpacking 3,743 kB will be freed.
Do you want to continue? [Y/n/?]
Get: 1 http://gb.archive.ubuntu.com/ubuntu/ trusty-security/main dkms all 2.2.0.3-1.1ubuntu5.14.04.5 [65.4 kB]
Fetched 65.4 kB in 0s (469 kB/s)
(Reading database ... 483437 files and directories currently installed.)
Removing shim-signed (1.33.1~14.04.4+13-0ubuntu2) ...
Removing shim (13-0ubuntu2) ...
dpkg: warning: downgrading dkms from 2.2.0.3-1.1ubuntu5.14.04.10 to 2.2.0.3-1.1ubuntu5.14.04.5
(Reading database ... 483420 files and directories currently installed.)
Preparing to unpack .../dkms_2.2.0.3-1.1ubuntu5.14.04.5_all.deb ...
Unpacking dkms (2.2.0.3-1.1ubuntu5.14.04.5) over (2.2.0.3-1.1ubuntu5.14.04.10) ...
Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
Setting up dkms (2.2.0.3-1.1ubuntu5.14.04.5) ...

I then rebooted, and Wifi still wasn't working, so I did 'sudo apt-get purge bcmwl-kernel-source && sudo apt-get install bcmwl-kernel-source' and the Wifi device re-appeared in my Connections menu but said "device not ready" so I did another reboot, and my Wifi is now working again! Hooray :-D

So there's obviously some strange "interaction" between bcmwl-kernel-source, dkms and shim-signed ? I have no idea which package this bug should be filed against / moved to.