I encountered the same issue.
Armbian 23.8.1 Bullseye with Linux 6.1.50-current-rockchip64
Armbian 23.02.2 Buster with Linux 5.15.93-rockchip64
Working fine:
Armbian 21.08.1 Bullseye with Linux 5.10.60-rockchip64
Armbian 21.08.1 Buster with Linux 5.10.60-rockchip64
using this to test:
ethtool -s eth0 speed 10 duplex full autoneg on