There is no switch. Add one and link the devices to it. Click on the switch and add it to the network (make sure you add a switch and not a hub). Then, drag links from the switch to the computers, choosing the ports to connect. No Switch 1024 1024 100 False 0 2 119 full pc0 100 100 187,465 pc False False 0.0.0.0 0.0.0.0 0.0.0.0 gw lo lo0 100 101 pc0 lo0 lo 101 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip eth eth0 100 102 pc0 eth0 eth 102 False eth0 192.168.1.2 255.255.255.0 0.0.0.0 ip pc1 100 103 562,472 pc False False 0.0.0.0 0.0.0.0 0.0.0.0 gw lo lo0 103 104 pc1 lo0 lo 104 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip eth eth0 103 105 pc1 eth0 eth 105 False eth0 192.168.1.4 255.255.255.0 0.0.0.0 ip pc2 100 116 378,455 pc False False 0.0.0.0 0.0.0.0 0.0.0.0 gw lo lo0 116 117 pc2 lo0 lo 117 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip eth eth0 116 118 pc2 eth0 eth 118 False eth0 192.168.1.3 255.255.255.0 0.0.0.0 ip pc0 net_switch0 NeedsLinkToDevice pc1 net_switch0 NeedsLinkToDevice pc2 net_switch0 NeedsLinkToDevice Link Switch