You should just be able to connect S1 directly to your iMac. See pg 7 in the
Ref Guide.
No Ethernet in my home office, so my iMac is on WiFi. S1 is connected to a TP-Link TL-SG105 switch (cause I also have a Dock) and that's connected via adapter to one of the iMac's Thunderbolt ports (Carbon is using the Ethernet port).