IPv6 static configuration (Ubuntu 19.04)

I’m trying to implement a network for a project where i need a server, a virtual machine running Ubuntu 19.04, with two static ipv4 and ipv6 addresses (one on each interface on the machine) to connect 2 subnet, but editing my /etc/network/interfaces file doesn’t seem to work.

At the moment my configuration is this:

auto enp0s8 iface enp0s8 inet static     address 192.168.20.10     netmask 255.255.255.0     network 192.168.20.0     broadcast 192.168.20.255     gateway 192.168.20.1  iface enp0s8 inet6 static     address fc00::2:0:0:0:a     netmask 64  auto enp0s9 iface enp0s9 inet static     address 192.168.30.10     netmask 255.255.255.0     network 192.168.30.0     broadcast 192.168.30.255     gateway 192.168.30.1  iface enp0s9 inet6 static     address fc00::3:0:0:0:a     netmask 64 

Using the command ip addr show ipv4 works fine but i can only see one of the 2 static ipv6 addresses (every interface also has its fe80: link-local address). How can i fix this?