Apple G4 with MacOS 9.1 unable to connect to Debian 2.2 box

[Cleto Pescia <cleto@eurisco.com>]

Hello,

I've run into a weird problem trying to have a PowerMac G4 with MacOS 9.1
connect to a Debian Linux 2.2 box (kernel 2.2.18).
A friend of mine has a small network of Macs, with several releases of
MacOS, all connected to a Debian 2.2 box acting as firewall / IP
masquerading server for Internet connection. Netatalk is installed and
working as expected, even on the G4. What does not work at all is the
TCP/IP connection between G4 and the Debian server. Only a tiny fraction
of packets is detected by tcpdump when using ping. But ping works from and
to the G4 for all other systems. All IP addresses used internally are
static and belong to the 192.168.1.0 Class C, with the Debian systems'
Ethernet interface configured as 192.168.1.1.
Oddly enough, when I substituted the Debian box with a similar
FreeBSD server, the problem disappeared.

Does anyone know if this problem is due to a flawed TCP/IP stack in
MacOS 9.1?

Any hint is welcome.

Cleto