Hi Smidsy,
Gemini-1 didn't have support for Ethernet. RS232/Serial is the main interface mechanism. The Feature port, with some additional hardware, could be used as an extra serial port, but not for Ethernet. If you want to control it over Ethernet, you'll need some Serial over Ethernet (or Wi-Fi) adapters that can convert between the two, but only serial should be connected to Gemini-1.
Regards,
? ? -Paul