Can't view Wifi networks after upgrading to Ubuntu 16.04

Solution 1:

I think its network manager issue. I had same problem with Intel Wireless-AC 7260.

I executed iwconfig - and the card was there but it was down (iwlist scan failed) - so I run these commands to bring it up manually:

sudo ifconfig wlp4s0 up
service network-manager restart

and it appeared in gnome just like a charm.

Solution 2:

modprobe: ERROR: could not insert 'wl': Required key not available

You need to turn off the secure boot.

Secure Boot is a security standard developed by members of the PC industry to help make sure that your PC boots using only software that is trusted by the PC manufacturer

Turn off the secure boot
Remove bcmwl-kernel-source
```
sudo apt-get purge bcmwl-kernel-source
```

Re-install bcmwl-kernel-source and the kernel header:

sudo apt-get install linux-generic bcmwl-kernel-source

Reboot

Solution 3:

For me, this command worked:

sudo /etc/init.d/network-manager restart

I used to need this command for my Chromebook running 15.04 whenever it woke from suspend. It came from some thread.

EDIT:

So this is only a temporary solution. To make it permanent, I put it in a script somewhere (for me ~/bin/fixwifi) then symlinked that script to the /etc/rc2.d with the name S06fixwifi.

In other words

Make a script somewhere with this text in it:

#!/usr/bin/env bash
/etc/init.d/network-manager restart

Make it executable with

chmod a+x <scriptname>

where scriptname is the name of the script you just made.

Then symlink it into the startups

sudo ln -s  </path/to/scriptname> /etc/rc2.d/S06fixwifi

Solution 4:

I had the same (with an Apple PowerMac 13" 2015) when I updated to official 16.04 Ubuntu today - with Unity. Before I used the latest 16.04 preview.

So there is IMHO two problems. One is that with the latest 16.04 kernel (4.4.0-21-generic) the firmware (as far as I understand it) makes the Broadcom 43602 WIFI chip not to work when booting initially. After suspend resume or

 sudo rmmod brcmfmac
 sudo modprobe brcmfmac

fixed the issue.

For whom it will interest: Still then suspend and resume didn't work any more as the box resumed automatically after 2-3 seconds. This seems to be a common problem. Description see https://bugzilla.kernel.org/show_bug.cgi?id=101681 . In my place an

 sudo cat > /etc/rc.local <<EOF
 echo LID0 > /proc/acpi/wakeup
 echo XHC1 > /proc/acpi/wakeup
 EOF

did the trick.

Solution 5:

for me it was enough to re-install the driver, first restarting the service to get it working

service network-manager restart
sudo apt-get purge bcmwl-kernel-source
sudo apt-get update
sudo apt-get install bcmwl-kernel-source

I was upgrading hp dv4 from 14.04 to 16.04