If the Intel wireless adapter you are using is listed below, please upgrade your driver to Intel PROSet/Wireless WiFi Software version = 20.70.0 (or higher version) to resolve the connectivity issues in 802.11ax routers.
In total we wanted to offer an answer that could be easy to follow and covered most Broadcom Cards / Drivers. After you follow this guide, you will NEED to test your wireless connection for at least 2 hours (I actually recommend 8 hours) with another device in either Ad-Hoc Mode, Infrastructure Mode or Both. Common problems that will be solved (Apart from drivers not installing) are:
There are dozens of Broadcom wireless cards and more seem to appear every day. The key to finding the correct driver for any network card is what is known as the PCI ID (PCI.ID). To find out which PCI.ID you have, we proceed to opening the terminal by pressing CTRL+ALT+T (It should open a window with a blank background) and inside this terminal we run the following command:
In hardware like the Lenovo S10-2, if your wireless card gets stuck trying to connect to an SSID (keeps trying to connect), then the alternative to get it working would be to install the bcmwl-kernel-source package (Remove any other installed packages related to it). Read the Debugging section below for more information regarding this wireless device.
If your laptop does not detect your wireless card some users have mentioned that using rfkill unblock all will solve the problem. Others simply turned the WiFi switch on their laptops off and then on again (Physical switch available on this laptops). For more information about rfkill please read rf kill unblock all DOES NOT WORK!
For all Wireless cards in general, it is very important to also take into consideration the network devices you are using (Routers, Switches, Wireless Channels and Wireless Bands, etc..). With this information you will be able to evaluate better what the source of the problem could be when you arrive at a dead end. An example would be the Lenovo S10-2 which uses the 14e4:4315 rev 01 PCIID. Even after installing the correct driver the user would end up in a \"trying to connect\" loop. It would see the wireless SSID but when trying to connect to it, it would enter an reconnecting loop.
The solution was that this particular wireless device did not support 40 Mhz channels nor does it support 802.11N. The router in that case was actually broadcasting with a forced 40 Mhz and on WiFi-N only. When the router was set to Auto mode and 20/40 Mhz Channel, the wireless card worked correctly. This is a case scenario that also repeats in other cases, so a proper evaluation of the network equipment would help a lot.
when doing a dmesg and your wireless connection drops often (Several times an hour or a day), the issue here might be that you are inside a wireless signal that is used as a Wireless Bridge (2 Routers sharing the same SSID and connection). This can happen with modern Routers that have the ability to extend the wireless connection by offering the same SSID. your wireless connection might drop because you might be between both routers and the signal strength between both is almost the same.
If your connection drops very often, it means you are almost in the middle of both router devices. To lower or eliminate the dropping rate of your wireless device, try to position yourself where your wireless card can see only one router or at least one of the routers has a higher signal strength than the other one.
There are also some techniques to force the wireless device to only connect to a specific router by setting the BSSID to the MAC Address of the router you wish to connect to. This will force your wireless device to ONLY connect to it.
Finally I've solved the problem myself, but I'm not sure how. I was about to compile the driver with the source from broadcom.com and instructions provided in _sta/README.txt, but at this step of the instructions
For pci.id 14er:4727--which holds in my case):Wireless does not work anymore after software update with Ubuntu 12.10 on a Dell Latitude E6230and How do I get an Acer Npilfy 802.11 (BCM43225) wireless card working who refers to the former.
Unfortunately, the wireless card is off whenever I reboot, so I created a script with the above two modprobe commands to execute whenever I reboot. This will have to do until Ubuntu 12.04 is updated with a fix.
In fact, my PCI.ID is 14e4:4727, which, according to the table, requires the installation of the package bcmwl-kernel-source. This package was perviously installed on my computer, but the Wifi wasn't working (no detection of any wireless network, since the upgrade to Ubuntu 16.04). I instead tried to install the firmware-b43-installer following Luis Alvarado's answer (using firmware-b43-installer is an alternative already pointed out in his post), and it worked !
For anyone else who is getting the \"wireless is disabled by hardware switch -a\" message under wireless (you'll see it by clicking on the icon) - and it's \"hard block\", that may work in any model (that is working for me in netgear \"wireless USB adapter\", haven't checked the others, but it may work).
After you've uninstalled b43-fwcutter reboot your computer. NB if you've no access to a wired network on your machine you will need to download the b43-fwcutter package manually from here, as well as your card's driver from here. My card is the 4311 so I download the broadcom-wl-4-150-10.5.tar.bz2.
One odd behaviour: when I tried to install the driver it said it alreday had the best driver installed. I unistalled the driver, then forced it to install this driver. Windows complained a little because it could not verify the driver, but nevertheless it installed and one reboot later the wireless adapter is working. 1e1e36bf2d