Hello Luca,
The osn provider basically only connects the vnics to the osn networks, items like dhcp must be handled on the osn networks itself.
Have you tried connecting any nics manually and checking connectivity between them?
No connectivity with static IP's could hint at some configuration problems. Are osn/ovs set up correctly? Firewall blocking traffic?
Can you please send us a more detailed descirption of your env (ip addr, brctl show, ovs-vsctl show)?