Ubuntu KVM guest os network

 On Ubuntu 20.04

You can use the default setting first:

If the guest OS cannot connect to internet, you may try the host nic and bridge it:

If that is not okay, you may need to create a new network source. The easiest way is to install VMWare workstation or Virtual box. They will create the needed network configuration for their VMs. Now you can use the network source created by them. Here is an example: