Ubuntu Server Set Static IP Address

In order to change from DHCP to static IP address, edit the contents of /etc/netplan/00-installer-config.yaml

# This is the network config written by 'subiquity'
network:
  ethernets:
    ens160:
      dhcp4: no
      addresses: [10.128.20.41/24]
      gateway4: 10.128.20.1
      nameservers:
        addresses: [10.128.20.21, 10.128.20.22]
  version: 2

svae the file, and do:

netplan apply

or reboot the server.