Depending on your use case, this may not apply, but since I don’t want to take a chance of doing anything to my main network, I want it to be isolated.
Configure a NAT virtual network in virt-manager:
Edit – Connection Details – Virtual Networks
Add New (+) – Name it – Forward
Change network address scheme as desired, uncheck Enable DHCPv4 (note Gateway for later) – Forward
Leave IPv6 unchecked – Forward
Select Forwarding to physical network, Destination should be your active host bridge device (br0 in my case), and mode should be NAT.
Since we are using our first VM for DHCP, the DNS Domain Name doesn’t matter. – Finish