I believe I'm having a similar issue. I'm running the Renegade Rockchip Libre Computer ROC-RK3328-CC-V1.3-8 and I've tried 6.12.32-current-rockchip64 as Debian IOT Minimal and as the Ubuntu Server versions from https://www.armbian.com/renegade/. Unfortunately the onboard ethernet phy is not working but I can use a USB ethernet just fine.
I'm not super sure where to start troubleshooting other than a binary search for the version that broke things. If more info is needed from my setup I'm happy to post, let me know.
