Comment # 3 on bug 1211325 from Marius Tomaschewski

Enabling forwarding (`net.ipv6.conf.all.forwarding = 1` in /etc/sysctl.d/..),
installing and configuring `radvd` on the VM _host_ is the right approach.

Overriding the managed bit in of the router advertisement locally with
`DHCLIENT6_MODE=managed` will cause to issue DHCP6 request and assign IP,
but there will be still no (default) routing in the VM.

See also:
https://github.com/openSUSE/wicked/wiki/FAQ/#q-why-is-dhclient6_modemanaged-insufficient-when-ipv6-router-advertisement-is-missed

-> INVALID IMO.