# Pastebin KfepW47y
Variant 1:
---
version: 1
config:
  - type: physical
    name: ens3
    subnets:
      - type: static
        control: auto
        address: 176.9.X.X
        gateway: 176.9.X.Y
        netmask: 255.255.255.255
  - type: physical
    name: ens3:0
    subnets:
      - type: static6
        control: auto
        address: 2a01::XX
        gateway: 2a01::XY
        netmask: 64

Results in

auto lo
iface lo inet loopback
    dns-nameservers 213.133.98.98 213.133.99.99 213.133.100.100

auto ens3
iface ens3 inet static
    address 176.9.X.X
    gateway 176.9.X.Y
    netmask 255.255.255.255

auto ens3:0
iface ens3:0 inet6 static6
    address 2a01::XX
    gateway 2a01::XY
    netmask 64

-> The static6 seems to be invalid, Ubuntu can't up the interface