I used both buster and ubuntu images (Armbian_5.91_Nanopineo4_Debian_buster_default_4.4.179_desktop.img and Armbian_5.90_Nanopineo4_Ubuntu_bionic_default_4.4.179_desktop.img), both have no wifi, only show "device not ready". So I extracted firmware from official friendly desktop image and unzip to /lib/firmware/rkwifi/ and wifi works. I'm a newbie and hope this could be fixed properly soon.
For those new to linux like me, download the attachment, extract everything to /lib/firmware/rkwifi/, reboot and wifi should be there.
ap6212.zip
Sun Xuan got a reaction from guidol in A temporary fix for Nanopi NEO4 wifi "device not ready"