I think the 6100F is a modem/router. It has only one Ethernet port in it, but when it's in "router mode" (which was the default for mine) you have to connect an Ethernet patch cable from the 6100F's lone Ethernet port to an Ethernet multi-port hub or switch. Then you can connect multiple computers to the switch.
I haven't been able to get my 6100F to work, by the way.