This is a fresh install of RHEL 7.5

First install the packages as shown below.

yum install qemu-kvm libvirt

Now install the additional recommened virtualization packages

# yum install virt-install libvirt-python virt-manager virt-install libvirt-client 

Now restart libvirtd

# systemctl restart libvirtd

 
Now you should be able to launch virt-manager from your remote machine and add a connection to your new virtualization host.

Special note. Make sure that you disable NetworkManager

# systemctl stop NetworkManager
# systemctl disable NetworkManager