According to MacFixIt, connecting a Mac OS 9 (or earlier) computer and a 10.4.9 computer, using Apple File Sharing, have been unable to transfer files between the two computers.
Apple has a solution; in the Terminal, enter this command on a single line, and hit Return:
sudo defaults write /Library/Preferences/com.apple.AppleFileServer TCPQuantum -int 327680
(Make sure the command is all on one line, the format can be seen in the KB article)
According to the article:
Adjusting the TCPQuantum parameter for the AFP server will apparently prevent the timeouts and disconnects between the two operating systems. TCPQuantum in AFP-speak represents a maximum size for a block of data being transferred to or from an AFP server; increasing the amount lowers the number of requests the server has to make for data at the expense of a gradual increase in overhead. More …