Some users will have issues creating ipv6 subnets in Synology DSM.

To do so, use the command line

docker network create --ipv6 --subnet 2001:db8:85a3::8a2e:370:9100/120 --gateway 2001:db8:85a3::8a2e:370:9101 --ip-range 2001:db8:85a3::8a2e:370:9100/24 --subnet 192.168.225.0/24 --ip-range 192.168.225.0/24 --gateway 192.168.225.1 container

So:

  • The first subnet (xxx9100) is the IPV6 subnet you have selected. Use an IPV6 generation tool to find one for yourself
  • The second entry (gateway) is the gateway address of the Docker network adapter
  • The third entry (ip range) is the range the docker network adapter will issue
  • The fourth to sixth entry is the ipv4 equivalent. leave these out if you dont need them
  • The seventh entry (container) is the name of the container network

    Make sure you have enabled IPV6 on your SYnology primary network adapter and that it has received an address from your IPV6 router (i.e. your router). Once done, make sure on your router you add a static route for the subnet to the Synology interface (not the Docker interface).