Fix netplan gateway4 deprecated

 

            routes:
                - to: default
                  via: 192.168.10.1
 

example:                  
network:
  version: 2
  renderer: networkd
  ethernets:
    eno1:
      dhcp4: false
      dhcp6: false
     addresses:
      - 192.168.10.10/24
     routes:
      - to: default
        via: 192.168.10.1
     nameservers:
       addresses: [192.168.10.1]

Fix permissions:
chmod 600 /etc/netplan/your_config_file.yaml