RockPi S Ethernet 10mbps not working


I’m trying to get a RockPi S connected by a slow ethernet connection with 10mbps (half or full duplex) but it doesn’t seem to work. If I test with a 100mbps connection, everything works fine and as expected.
Using 10mbps, it seems to look fine, e.g. ethtool shows a link with 10mpbs, advertised modes look fine but it the RockPi S doesn’t even retrieve an IP via DHCP. If configuring a static IP, no ping to any address beside the own IP address is possible.
I’m using latest debian-based armbian 23.8.1 stable and performed apt-get update & upgrade.

Anyone encountered the same problem and has some hints?
Unfortunately I’m not a linux pro so I’m a bit stuck unfortunately but I’m happy to provide any missing information or execute commands on the RockPi S and post the results here.