gigabit fiber works fine, amazon sells splitters, split tx and loop back to rx on the tx side. Rx side just works. you need to use a file transfer tool intende

gigabit fiber works fine, amazon sells splitters, split tx and loop back to rx on the tx side. Rx side just works. you need to use a file transfer tool intended for unidirectional transfer (e.g. multicast) otherwise you will have failure from lost packets. If you don't require high speed just use RS232.