The Broadcom drivers available with Solus do not work for all models (specifically for those below bcm4312). I have an old Dell laptop with the bcm4311, and it was always a hassle to get it installed in any version of Linux (Manjaro being the exception, as the correct drivers are included with the ISO) until I read somewhere that once the Broadcom drivers were properly extracted, they could be copied and used on any system. So, if anyone is struggling with installing Broadcom wireless drivers for a bcm4311 (it may work for other models also), I have uploaded the b43 firmware folder and if you follow the instructions below, it should install without a hitch.
Download the archived file b43.tar.gz to your Downloads directory.
Open a terminal session. Enter or copy/paste the commands in bold.
you@yourpc ~ $ sudo su
root@yourpc # cd /home/you/Downloads
root@yourpc /home/you/Downloads # tar -xzvf b43.tar.gz -C /lib64/firmware
[This will copy the B43 firmware folder and its contents directly to your /lib64/firmware folder and list each file as it copies.]
root@yourpc # exit
Close your terminal session and all other open applications.
Reboot your system.
Your Broadcom wireless should start automatically at boot.