Comment 15 for bug 1531184

The reference paelzer references is related to Ubuntu 14.04. In Ubuntu 18.04, "/etc/netplan/01-network-manager-all.yaml" defaults all network device management to NetworkManager. Therefore any solution will have to be to NetworkManager's systemd service file.

My solution which I've tested and consistently raises dnsmasq up only after the interfaces are up in 18.04 is as follows:

sed -i 's/After=network.target/After=NetworkManager-wait-online.service/' /lib/systemd/system/dnsmasq.service

The 18.04 askubuntu related link is:
https://askubuntu.com/questions/1124530/systemd-starts-dnsmasq-before-starting-network-manager/1154727#1154727