By open and routed you mean create a open virtual network from the virtual network options and then add the route using the route option of my isp provided router?
Either create a new network or edit the default one:
sudo virsh net-destroy default
sudo EDITOR="sed -i -e s/nat/route/" virsh net-edit default
sudo virsh net-start default
Guests will likely need a cold restart to apply the changes.
Added cockpit, networking