I recently upgraded the Pi of my Zynthian build from a 2 B+ to a 3 B+ due to the low processing power of the 2 B+ causing issues with sampling software. This upgrade fixed that issue, however I am now having problems with WiFi connectivity.
On first boot using ethernet, I was able to access the web interface and set up WiFI. I then rebooted without ethernet to find that it was not online, and I could no longer access the web interface.
Booting it a third time, running ifconfig I found that the interface was not being recognised, even after setting the correct WiFi locale and trying to start WiFi from the admin menu of Zynthian.
I have also tried installing the packages suggested in this post with no luck:
apt install wpasupplicant firmware-brcm80211
In dmesg, we see an error -2 when loading the brcm firmware:
[ 3.287408] brcmfmac: brcmf_fw_map_chip_to_name: using brcm/brcmfmac43455-sdio.bin for chip 0x004345(17221) rev 0x000006 [ 3.289863] usbcore: registered new interface driver brcmfmac [ 3.324797] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43455-sdio.bin failed with error -2