To get two ports out of my server (exteme modded mac mini) I assigned/bridged thundebolt port as ethernet port, thunderbolt to ethernet conversion cable, instantly have two ethernet ports. On other servers you could do this with usb ports. Or off the shelf servers such as Antipodes and Sonicorbiter I9 which have two ethernet ports built in, I9 also has advantage of being optical out.
Ethernet direct out of server beneficial if running separate streamer/end point, in this case it bypasses switch or router, also useful for direct out to the FMC's, Optical conversion is best way to isolate streamer/dacs from network noise. I can just about guarantee the future will be all optical network solutions.
FMC is fiber media converter, this converts ethernet to optical, you can do this on cheap with FMC like TP link MC220 or you can go higher end with Sonore opticalrendu products.
For those wanting to learn more about streaming, audiophilestyle.com forum is the place to go.https://audiophilestyle.com/forums/