Ubuntu – Slow connection with Broadcom BCM43142 on Ubuntu 16.04

Important note

An updated revision of bcmwl-kernel-source that should fix the issues on kernel 3.8.0.xx has been rolled out to the precise-updates archives. Please make sure to upgrade your system before considering any of the workarounds posted in this Q&A.

(thanks, @gertvdijk for the headsup)

Original answer

The issue you are dealing with seems to mainly appear on Ubuntu 12.04.3 LTS with the backported kernel 3.8.0-xx installed.

Please take a look at this bug report. As you can see it's a known problem and many different workarounds exist.

What worked for me was installing the latest bcmwl-kernel-source from Raring. You can find this package here. Make sure to download the right one for your system, e.g. this one if you have an amd64 machine.

You can install the package via:

sudo dpkg -i ~/Downloads/bcmwl-kernel-source_6.20.155.1+bdcom-0ubuntu6_amd64.deb

Of course you will have to change the path to the deb file in accordance to where you downloaded it to.

You might have to execute the following command afterwards to get your wireless up and running:

sudo modprobe wl

Source: http://ubuntuforums.org/showthread.php?t=2155228&page=2&p=12765664#post12765664

I've been struggling with the same issue with Broadcom BCM43142 on my HP Envy 15 Touchsmart, Ubuntu 14.04. The Wifi card performance deteriorated after an update I did with Software Updater.

I tried purging and reinstalling bcmwl-kernel-source, installing firmware-b43-install and b43-fwcutter in various combinations. Nothing worked.

In the end, I had to downgrade bcmwl-kernel-source to a lower version by doing the following in the terminal:

sudo apt-get remove --purge bcmwl-kernel-source
sudo apt-get install bcmwl-kernel-source=6.30.223.141+bdcom-0ubuntu2
sudo reboot

It's not ideal, but the wifi now works as it did before the update.