If dhclient works to get an IP address, then I suspect your routing table.
2013-02-03 Sunday 13:10 hek * sys/init.c: set cwd to sysdir for modules
which sets default directory to $SYSDIR for all modules (incl. XIFs). This broke Fopen("svethlan.inf",0) code in the Svethlana driver which expected to load the inf file from the boot drive and failed.
2. Default MAC address for both Svethlana and Ethernat: 01:02:03:04:05:06. This MAC address causes headaches to my router and perhaps to Darren's as well, i.e. it doesn't work.Since I don't have source code from Svethlana, I can only read ethernat.c: