Recover Lost WiFi Network

Question

I just installed Kubuntu 20.04.1 to a dual-boot partition on my Macbook Pro (late 2012). On the live usb, I could see my usual WiFi network, and connected to it.

After the install, I could still see the WiFi connection in my system settings (listed as 'never used'), but I couldn't connect to WiFi. At that point, I removed the connection with the minus button, trying to get things working.

Even though I checked "install third party software" in the installation settings, I figured it was a broadcom issue, and after installing the firmware-b43-installer package, I can connect to WiFi again (hooray!).

Unfortunately, now I can see all the local networks except my usual WiFi network (the same one I removed earlier with the minus button, when the firmware was missing). How do I get it back?

I tried to enter the information manually (from the network settings panel on a separate computer running Kubuntu 20.04.1, which can successfully connect to the network in question), but the new install still won't connect.

At this point I am out of ideas, and I would sure appreciate any help you can offer, thank you for reading!

Answer 1

I had the same problem on my late-2011 Macbook Pro. I dual-boot this old Mac with High Sierra & Ubuntu 20.01.1. It had been working almost perfectly until today. I started up & no WiFi. ip a didn't even show a wireless adapter - what a rude mess!

I verified hardware was OK by booting into High Sierra - it worked... So - a software issue. A search turned up this question, but no answer (as I write this). The search also turned up this: "How to Fix No Wireless Issue...", which ultimately solved the issue. Here's the relevant part:

Skip ahead to Method 2: Fix no WiFi in Ubuntu with broadcom wireless adapters

$ sudo lshw -C network
...
product: BCM4331 802.11a/b/g/n

OK - that was as expected...

$ sudo apt remove broadcom-sta-dkms bcmwl-kernel-source

The response here was to the effect that there was nothing to remove?

$ sudo apt install firmware-b43-installer

Fortunately, the late-2011 MBP has an RJ45 jack & I was close enough to a switch to plug in.

After completing this step & re-booting, all is well again - as promised. I found my WiFi AP, re-entered the password & disconnected the Ethernet again.

FWIW:

I tried Method 1 before going on to Method 2, which uncovered an oddity:

When I reached Step 3, the Software & Updates window, Additional Drivers tab showed that a driver was already loaded for my WiFi device. The .iso file download seems unnecessary. In fact, for users with Broadcom w\WiFi adapters, perhaps the following procedure is more to the point:

1. Verify Broadcom hardware product installed:

$ sudo lshw -C network

2. Install Broadcom 43-series firmware

$ sudo apt install firmware-b43-installer

3. sudo reboot

Answer 2

Many thanks to those who answered, it turns out my issue was related to 5GHz reception.

My 'missing' network is 5Ghz, which isn't supported by firmware-b43-installer. I could see other neighborhood signals, but apparently these were all lower frequency networks.

After pulling my hair out for a few days, all I had to do to 'recover' my 'missing' network was navigate to the Discover Software Center Settings > Software Sources > Additional Drivers, and select the proprietary Broadcom driver that was actually already included with my install, but for some reason not active by default.