@root-stas Thank you for your guide.
Unfortunately I still don't have working wired network on my x99 pro plus / x88 pro x3 / Transpeed X3 Plus. (these are the same, some said)
I have tries some meson-sm1-sei610-ethfix.dtb -s, I have seen the ethernet device, but it simply doesn't ping. DHCP is not working, I changed the network adapter's setttings to autonegotiation off, 100mbit, static ips, nothing helped. My dts file's netwotk part from android is so different than the ethfix dtb/dts's.
I am thinking about using the Ubuntu 20 with 4.xx kernel. Would that work with my extracted android dtb?
This is my ethernet parts from the dts: