Both for Satellite 6.18 and 6.19,  In "Chapter 3. Preparing environment for Satellite Server installation" of the Connected Network Installation guide, We see this point mentioned:

Procedure:

1. If you need to prevent the DHCP Capsule from pinging hosts to check for available IP addresses, disable DHCP IP address pinging:

1. satellite-installer --foreman-proxy-dhcp-ping-free-ip false

This does not look like the right place to do any installer execution at all. If someone needs to do this, then this point needs to be moved after Chapter 4, preferably in Chapter 6. 

The exact same problem exists in the Disconnected installation guide as well.