We are trying to get a new server running 18.04 LTS to connect to the internet, but no luck thus far. The router doesn't distribute DHCP, so we have a static IP assigned to the port the server is connected to. We tried following the instructions here: https://www.howtoforge.com/linux-basics-set-a-static-ip-on-ubuntu
That didn't work - still no network connection. Note that there was no file named 01-netcfg.yaml in /etc/netplan. There was another yaml file that was named 50-netcfg.yaml and that's the file we edited.
network:
  version: 2
  renderer: networkd
  ethernets:
    eno1:
      dhcp4: no
      dhcp6: no
      addresses: [204.xxx.xxx.108/25]
      gateway4: 204.xxx.xxx.1
      nameservers:
        addresses: [8.8.8.8,8.8.4.4]