I’m trying to use Manjaro on a 2012 iMac13,2, which uses the Broadcom BCM4331 wifi card. I’ve installed the b43-firmware as suggested in the Archwiki article on Broadcom Wireless. And the b43 module is installed and running. Wifi works, I can see available access points, but only those using 2.4 Ghz. If I connect to 2.4 Ghz with my router the connection is super slow (around 5 Mbps). But no 5 Ghz channels are detected. (With other computers I can easily get 200 - 300 Mbps on the 5 Ghz channel of my router.)
dmesg | grep -i b43 shows a message saying 5 Ghz is unsupported:
[ 17.881402] b43-phy0: Broadcom 4331 WLAN found (core revision 29)
[ 17.881812] b43-phy0: Found PHY: Analog 9, Type 7 (HT), Revision 1
[ 17.881824] b43-phy0: Found Radio: Manuf 0x17F, ID 0x2059, Revision 0, Version 1
[ 17.881827] b43-phy0 warning: 5 GHz band is unsupported on this PHY
[ 18.048613] b43 bcma0:1 wlp4s0b1: renamed from wlan0
[ 22.348399] b43-phy0: Loading firmware version 784.2 (2012-08-15 21:35:19)
[ 22.584399] b43-phy0: Loading firmware version 784.2 (2012-08-15 21:35:19)
[ 434.967468] b43-phy0: Loading firmware version 784.2 (2012-08-15 21:35:19)
[ 847.895001] b43-phy0: Loading firmware version 784.2 (2012-08-15 21:35:19)
[ 1260.991725] b43-phy0: Loading firmware version 784.2 (2012-08-15 21:35:19)
[ 1673.913193] b43-phy0: Loading firmware version 784.2 (2012-08-15 21:35:19)
[ 2086.975572] b43-phy0: Loading firmware version 784.2 (2012-08-15 21:35:19)
But BCM4331 does support 5Ghz. Is it really possible that the b43 module does not? I read somewhere that the brcmfmac driver (part of brcm80211) does support 5 Ghz, but it’s not listed as working with BCM4331. Is there a way to try and force it to load and see if if works?
I did also try the proprietary driver broadcom-wl. This works with 5 Ghz, but it’s outdated and doesn’t support 80211w Management Frame Protection protocol. If I disable Management Frame Protection in my router, then I can connect to the 5Ghz channel. But doing so downgrades the security of my router and for all other devices connected to it.
Is there any solution to this? Can I get b43 to work with 5 Ghz somehow? Can I force the brcmfmac driver to be used and will that work with the BCM4331 wifi card? Can I get broadcom-wl to work with Management Frame Protection? Also, I guess, why is the connection to 2.4 Ghz with b43 so slow?
Broadcom is a chip vendor and it is quite possible that Apple has made custom specifications - really difficult to know.
EDIT:
If I recall correct Management Frame Protection is part of the WPA3 specification.
Not all wifi cards supports WPA3.
If your router allows for creating multiple access points you can create a separate access point for the mac using WPA2.
I have done something similar in my network because not all devices support WPA3 (e.g. Nintendo) so instead of downgrading the entire network I have created an iot network which uses WPA2.
Thanks for the suggestion. I guess I’ll, switch back to broadcom-wl and give that a try. Although, I think my router is supposed to fallback to WPA2 so it seems like if that were the issue it should have worked when I tried it before.
Any thoughts about why with the b43 driver 5 Ghz doesn’t work? That’s really the main question I’d like to figure out. I’d rather use a driver that still gets updates. Or why on 2.4 Ghz it’s incredibly slow with b43?
I’ve already read the Arch wiki article on Broadcomm wireless extensively and searched all over the internet for explanations or other people with the same issue.
I suppose my last resort might just be buying a usb wifi adapter that is hopefully better supported by linux.
If the broadcom-wl driver work with 5GHz over WPA2 then it support 5GHz - but as you do not want to use switch the network to WPA2 your options are limited to
if router support a secondary AP using WPA2 it will work
if router do not support a secondary AP buy a USB dongle
My router does allow for a second access point. I tried this and setting it to WPA2 allows me to connect to 5 Ghz with the broadcom-wl. I also have the option to just disable Management Frame Protection on the second access point.
I’m not in love with this solution though. It would be nice if I could figure out why the connection over 2.4 Ghz with the b43 driver is so slow. The computer is about ten feet from the router. It should be able to get a couple hundred Mbps over 2.4 Ghz.
Thanks for the link. By “hope” I just meant, I’ll hope some other totally unexpected issue doesn’t come up, because configuring this iMac reminds me of when I first started using Linux twenty years ago and there were all sorts of things you had to manually configure and that didn’t work out of the box. Normally my policy is: Only computers that are all Intel. It just makes life easier. But the iMac was free and it has a nice screen.
I also found this link that lists some usb wifi adapters that work in Linux. It has a few more options.
The point being - not all is compatible - so one has to research.
Some USB WiFi dongles requires a custom package to be workable - others have support out-of-box.
Possibly Apple’s implementation of the chip - they are known for protecting their brand - and Apple doesn’t care about e-waste - all they care about is turnover - even if they no longer support the hardware themselves - their implementation choices will haunt those trying to revive the hardware.
wpa3 to wpa2 for me the other day and all my devices are able to connect. with wpa3 all but one could.
with wpa3 it was behaving like a hidden network that wouldn’t function properly when i connected to it. I will create a guest network later with the device to have both.
