If you use
something like pfSense for a firewall, you can have it
provide addresses to the network. However, if you're not getting
addresses from the ISP or via a tunnel from he.net
or similar, you
should use something in the unique local range, which is fc:: /7.
Normally you'd use addresses starting with fd. Like RFC1918 addresses
on IPv4, unique local addresses are routeable, but not allowed on the
Forget the router.
It has to be done on YaST.
I'll have a look later.