Installing Ubuntu Server 24.04 LTS in an offline mode (no LAN cable or WiFi connected) leaves you with an unmanaged network interface which requires manual configuration post-install.
The interface enp4s0 is unmanaged by systemd-networkd and also the service itself is disabled.
NOTE: This guide applies to Ubuntu server. On Ubuntu desktop you have the NetworkManager service installed and the steps would be different.
To fix the problem follow the steps below:
Create a Brand New Netplan Configuration File
