# Pastebin uoO0FwGZ
ubuntu@rack-1-m2:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback
    dns-search maas
    dns-nameservers 192.168.10.5

auto eth0
iface eth0 inet manual
    mtu 1500

iface eth1 inet manual

auto juju-br0
iface juju-br0 inet static
    address 192.168.10.52/24
    gateway 192.168.10.1
    mtu 1500
    bridge_ports eth1

auto wlan0
iface wlan0 inet manual
    mtu 1500

source /etc/network/interfaces.d/*.cfg
ubuntu@rack-1-m2:~$