Why is my WiFi connection erratic after upgrading to 21.10?

Solution 1:

You have a Broadcom BCM4360 card, and you are currently using driver wl. There are old reports related to the Broadcom family stating that: 1) there are several available drivers (1), 2) people managed to get the WiFi working by trying alternative drivers. Perhaps this is what you did in the past. So you could try the same now. I will post guidelines, you could probably fill the gaps, if any.

Driver

There seem to be several drivers available, at least: bcma-pci-bridge (2), wl. You could try something like

$ sudo modprobe -r wl bcma
$ sudo modprobe bcm43

Firmware

You could also try updating firmware (3).

Driver configuration

Note also that, as per 2, your WiFi has two antennas. You might try changing the antenna. It is essential that you get configuration options with

$ modinfo wl

(or change wl with whatever driver you try).

Bluetooth

There is another card model listed (2) which has also integrated bluetooth, and it is often a source of interference, but it is apparently only included in iMacs. You could confirm this to rule out interference.

Related:

1. https://help.ubuntu.com/community/WifiDocs/Driver/bcm43xx
2. No Wireless When Install 14.04 on Macbook Pro
3. https://www.reddit.com/r/archlinux/comments/8dsdot/macbook_air_wireless_help/

Please post the following info

1. Output of commands

   $ uname -a
   $ sudo lshw -class network
   $ ls -al /etc/pm/config.d/
   $ ls -al /etc/modprobe.d/
   $ lspci -knn | grep Net -A4
   $ modinfo wl
   $ sudo iwlist freq
   $ sudo iwconfig
   $ inxi -Fxz
   $ nmcli device wifi list
   $ sudo lsmod | grep wl
   $ iwlist scan | egrep -i 'ssid|quality'
   $ lsusb
   $ usb-devices
   $ cat /etc/modprobe.d/wl.conf
   $ grep [[:alnum:]] /sys/module/wl/parameters/*
   

   You would get the wifi driver from command lspci -knn | grep Net -A4 above.

2. Full brand/model of your computer.