How are 'Novell Connections' numbers given out to wrkstns - I'm getting

I work in a school and we have labs. I just created a new 6.5 server, and
installed 4.91 clients on XP systems. This is a completely new set of
workstation software and a new server. I find half of the room gets the same
connection number as other stations on the network. Only the client that is
listed on the server's Monitor screen is still really working. The other(s)
with a dup 'Novell Connections' number is not connected to the server. Yet,
IP is still working fine, surfing the web works, connecting to other peer to
peer workstations works ... The real question is how to fix the problem of
the computers dropping off the server before even finishing logging in.
But, I would also, and maybe it is the answer, like to understand how the
Novell 6.5 server gives out connection numbers.