root@vps-de:/etc/swanctl # cat /etc/network/interfaces.d/50-cloud-init

auto lo
iface lo inet loopback
        # CA
        dns-nameservers 158.69.126.137
        dns-nameservers 2607:5300:60:9389:15:2:a:1000
        dns-nameservers 2607:5300:60:9389:15:1:a:1000
        # DE
        dns-nameservers 2001:41d0:701:1100::6530
        dns-nameservers 135.125.133.51
        # OVH
        dns-nameservers 213.186.33.99

#auto ens3
#iface ens3 inet static
#    address 135.125.133.51
#    netmask 255.255.255.0
#    gateway 135.125.132.1
#    mtu 1500

#iface ens3 inet6 static
#    address 2001:41d0:701:1100::6530
#    netmask 128
#    gateway 2001:41d0:701:1100::1
#    mtu 1500

iface ens3 inet manual

auto vmbr0
iface vmbr0 inet static
        address 135.125.133.51
        netmask 255.255.255.0
        broadcast 135.125.133.255
        gateway 135.125.132.1
        bridge-ports ens3
        bridge-stp off
        bridge-fd 0
        mtu 1500

iface vmbr0 inet6 static
        address 2001:41d0:701:1100::6530
        netmask 128
        gateway 2001:41d0:701:1100::1
        mtu 1500
        post-up ip -6 addr change 2001:41d0:701:1100::6530/128 dev vmbr0 preferred_lft 0

auto vmbr1
iface vmbr1 inet static
        address  10.133.0.254
        netmask  255.255.255.0
        bridge-ports none
        bridge-stp on
        bridge-fd 0
#       post-up ip -4 route add 10.133.51.0/24 via 10.133.51.1

iface vmbr1 inet6 static
        address fc00:41d0:701:1100::fffe
        netmask 64