I got it working using a different version of brcmfmac4356-sdio.bin/brcmfmac4356-sdio.txt. It is not committed to Armbian repository since it could break some other boards such as OPi3.   If you wish to try it out, backup the original ones and use the ones I'm providing here in attachment.   brcmfmac4356-sdio.bin brcmfmac4356-sdio.txt