Guys I'm with you! Unfortunately I do not have enough knowledge of linux to help you (
I have Z28 PRO RLT8211e + RTL8822bs no sd boot
I try https://github.com/ayufan-rock64/linux-build/releases/ rock64 image and found out that from version 0.5 eth does not work. looks like ayufan remove external phy support.
Do not forget that rockchip has https://github.com/rockchip-linux/rkdeveloptool this util can write\read partition\loader\gpt table via maskrom