That cleared up some backgound - I didn't realize you couldn't login using the
virtual terminal with NIS (case 3).
Is it possible to ping the target system when no one is logged in? If not, then this
may point to the network being disabled when no one is logged in, this would
imply that network manager does not have the network up (which would
prevent NIS...). There are several other threads on this problem with network
manager (there is an option):
I was able to make it available to all users by opening the terminal, and switching to su, and running the "nm-connection-editor" command. That open the connections window as root.
With this you should be able to select "allow all users".
Now if you want you could also disable networkmanager (chkconfig NetworkManager off)
and enable network (chkconfig network on). If you do
this without a reboot you can use "service NetworkManager stop" and
"service network start" to start the networks.
This should make the network available at all times (to me, this would seem
to be the normal situation, but It is possible to get the network manager module
to work properly, though it isn't as well documented).