7.5.3 and later File Sharing
Any Mac running 7.5.3 or later can share the files of any Mac running OS 9 or later using built-in File Sharing using IP. What is not supported beyond 10.3 is File Sharing via AppleTalk. In addition, Sharing initiated from your 10.4 or later Mac to a Mac before OS 9 is not supported directly. So you will have to make the connection from the Older Mac end. Alternatively, you could install "Shareway IP" (a low-cost utility) on the older Mac and connect from the newer Mac.
The 6400 sometimes has trouble when connected to another computer directly, rather than through a Router, Switch, or Hub. The 6400 often has to be connected to an Active Ethernet port AT 6400 STARTUP, or its Ethernet port cannot be selected in the TCP/IP Control panel.
A good general description of this sort of connection process appears in this illustrated article:
Car1son's OS 9 to OS X 10.3 File Sharing Setup
Several links near the top of the page point back at Apple KnowledgeBase articles for network setup, etc.
Message was edited by: Grant Bennet-Alder