You need to use the iproute2 commands and ifconfig commands are deprecated.
ip addr flush dev eth0 # remove running ip config
ip addr add xxx.xxx.xxx.xxx/xx dev eth0 # set ip for dev eth0
ip addr show
ip route add default via xxx.xxx.xxx.xxx dev eth0 # set default gateway
It should work but i don't know how to make this survive a reboot, didn't have time to play with config files yet.
That worked liked a charm. Thank you, now we just have to figure out to make it persistent..
Remove /etc/systemd/network/10-dhcp-eth0.network and create a new file /etc/systemd/network/static.network with the following contents:
Then execute systemctl restart systemd-networkd.