This is another documentation issue in the text of the installer, this
time the message returned upon failure to connect to the network. The
message (in my case erroneously) jumps to the conclusion that the
network 'probably isn't using DHCP'. That's bound to confuse people most
prone to confusion - the less-experienced users.
I have no idea why the connection attempt failed the first two times I
tried. I just went all stubborn on the installer and repeated until it
gave up complaining and negotiated the connection.