Thanks,
I will try it.
I've tried Armbian Bionic (same as Armbian Stretch) nightly builds before, but I had no Wifi and max resolution was 1920x1080 (I have 2k monitor). Plus I did not see mali0 under /dev.
So I thought there's missing mali driver.
I am new in linux so sorry for noob questions...
EDIT:
JMCC, what did you mean Armbian Bionic Default image?
I've found only nightly builds working with kernel 4.2, updating kernel to 4.4 caused boot failure.
On the https://dl.armbian.com/rockpi-4b/, in the "Archive" folder I found 5.75 versions of Armbian with 4.4.174 kernels, but no boot again. Just red led blinking...
So I did not find a way how to get armbian bionic working with 4.4 kernel.
What am I missing?