I believe I am seeing the problem described 6 years ago in this thread:

I need help with IPX network in DOSBox

I notice that IP addresses display backwards on the PPC Mac IPXNET STATUS output, and I am unable to establish game sessions or ping with a Windows PC. When I do the exact same config on Intel Mac, IP addresses display correctly, and games are able to establish.

When I try to play between two G5 Macs, it also does not work. IPXNET seem to think they are connected, but PING does not work, and games will see each other(broadcast?), but can not actually communicate.

Is there perhaps a long standing endian bug or missing ntoa macro in DOSBox? Or a transition from inside the VM to outside the VM isn't converted?