The 400Kb was over my old Coaxial network at home. I have some old hardware which is connected to a coax hub. On the coax hub there is an aui-port which connects to the empeg.
FTP-transfers also top at about 400Kb...
If you use a full-duplex UTP-hub you could get as far as 1.2Mb/s, also with displayserver, as it uses a standard TCP-connection.

Frank van Gestel