Comment 37 for bug 1671951

Verification-done on bionic:

ubuntu@ip-172-30-0-140:/run/systemd/network$ lsb_release -cs
bionic
ubuntu@ip-172-30-0-140:/run/systemd/network$ dpkg -l netplan.io | grep ii
ii netplan.io 0.98-0ubuntu1~18.04.1 amd64 YAML network configuration abstraction for various backends
ubuntu@ip-172-30-0-140:/run/systemd/network$ dpkg -l systemd | grep ii
ii systemd 237-3ubuntu10.31 amd64 system and service manager
ubuntu@ip-172-30-0-140:/run/systemd/network$ cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by
# the datasource. Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    version: 2
    ethernets:
        eth0:
            dhcp4: true
            match:
                macaddress: 06:e0:25:2e:08:ef
            set-name: eth0
            ipv6-mtu: 5634
            mtu: 6666
            dhcp6: true
            dhcp4-overrides:
                use-mtu: false
            dhcp6-overrides:
                use-mtu: false
ubuntu@ip-172-30-0-140:/run/systemd/network$ sudo netplan apply
ubuntu@ip-172-30-0-140:/run/systemd/network$ networkctl
IDX LINK TYPE OPERATIONAL SETUP
  1 lo loopback carrier unmanaged
  2 eth0 ether routable configured

2 links listed.
ubuntu@ip-172-30-0-140:/run/systemd/network$ sysctl net.ipv6.conf.eth0.mtu
net.ipv6.conf.eth0.mtu = 5634
ubuntu@ip-172-30-0-140:/run/systemd/network$ ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 6666 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 06:e0:25:2e:08:ef brd ff:ff:ff:ff:ff:ff
ubuntu@ip-172-30-0-140:/run/systemd/network$