I installed default installation of armbian image with 4.9er kernel and installing omv 5.0 with armbian softy tool. Then I installed docker via omv webpage. On default the new iptables nft is used which breaks using "docker network create ..." because it seems iptable nft is still not supported using docker.
After changing iptables usage it worked:
Switching to the legacy version:
# update-alternatives --set iptables /usr/sbin/iptables-legacy
# update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy
# update-alternatives --set arptables /usr/sbin/arptables-legacy
# update-alternatives --set ebtables /usr/sbin/ebtables-legacy
Would be nice if the omv installation skript would be do these things automatically to avoid searching why "docker network create" is not working with strange error messages.