Thank you for the explanation and untill we get it sorted out for the upcoming release, I’ve used your information in a Wiki article.
https://endeavouros.com/docs/hardware-and-network/get-broadcom-working-on-an-installed-system-and-on-live-usb/
And welcome in the community, by the way
I’ll have to try this since i have a TP-Link Archer AC 1900 with the Broadcom 4360 chip. I was always hooking it up to Ethernet to install. I use the broadcom-wl-dkms and headers. My wifi connects instantly when it boots up and kalu runs instantly also. No issues other than installing it.
Thanks for the step-by-step guide.
Only warning i add here and that’s what happened to @nauticalnexus is that the kernel present in the iso wasn’t the the latest.
2 days after the iso was built there was some kernel update.
So instead of downloading the latest linux-headers is good to check which kernel version is in the iso with uname -r
It may require to download from arch linux archive.
Again the problem that happended here is that not all the packages were transfered through usb, so initramfs failed causing an unbootable system. (my gues)
That’s why downloading linux-header with the same kernel in the iso maybe simpler.
Thanks to my cell phone, taken as Ethernet, for the USB connection, I was able to have some inet for two months to be able to do my chores and be connected.
HI! I forgot about this. @fernandomaroto installing kernel headers worked perfect. Mac gets online no issues. That’s what was missing 
so we need to add linux-headers to be installed on the ISO ?
Hi, I want to install endeavour (offline install) on a mid 2013 Macbook Air, I booted into the live ISO and wifi is not working
but have you added the kernel headers to the ISO to be installed?
Thanks!
The reason I put a question mark is I’m not 100% sure with the offline install. I know the online has it for sure. I think it does but I won’t bet the farm. 
Device works intermittently
In some cases (e.g. using BCM4331 and b43-firmwareAUR), wifi connection works intermittently. One way to fix this is to check if the card is hard-blocked or soft-blocked by kernel, and if it is, unblock it with rfkill.
SSH freeze for BCM4331 with b43
The b43-firmwareAUR driver has been observed hanging in ssh sessions with BCM4331. Installing broadcom-wl and removing b43 solves it.
I have broadcom on all my systems and i don’t have this issue as they are newer chips. But, they are also on desktops & laptops seem to have different chips and issues.
yeah I did the installation on my Macbook and it worked out of the box, no problem
the only small thing is that it takes a little bit of time to connect, but it’s like 5 sec so not really an issue
Like @joekamprad said there is an issue with someof the broadcomchips where they don’t work on the live ISO because of one reason or another and you have to check a few things and you can get it working usually.
Do you know what chip it is?
lspci -k
BCM43224 chip
it could be that you need brcmsmac module and on ISO it loads broadcom-wl module so a simple
sudo rmmod wl
sudo modprobe brcmsmac
but first check if it is blocked
rfkill
I tried and it disconnected me from the network, I had to reconnect but no change
I’ll do some research, once again it’s no big deal
02:00.0 Network controller: Broadcom Inc. and subsidiaries BCM43224 802.11a/b/g/n (rev 01)
Subsystem: Apple Inc. AirPort Extreme
Kernel driver in use: wl
Kernel modules: bcma, wl
Confirm this solution worked for me with the similar 4313 chipset during installation process.
You can also check Wireless drivers page in kernel wiki other than the already linked archwiki.
shows here that wl module is still in use so it was not the output from rmmod and loading
brcmsmac module.