network:
version: 2
# renderer: NetworkManager
ethernets:
eth0:
addresses:
- 192.168.100.116/24
- 192.168.100.117/24
- 192.168.100.118/24
gateway4: 192.168.100.1
nameservers:
search: [google.com]
addresses: [8.8.8.8, 8.8.4.4]
eth0:1:
addresses: 172.16.1.69/32
netplan apply
If I didn't understand it in a wrong way, you create a subinterface (eth0:1) when you want to add an address that is in another subnet. If it's in the same subnet you just add the new address in the same interface