The data transmission over the switch of LANCOM devices only takes place on the port the target computer is attached to. Therefore the connections on the other ports are not visible.
For monitoring data traffic between ports, the ports must be set to monitor mode. In this state all data is issued, that is transmitted over the switch of the devices between stations of the LAN and WAN.
For the configuration with LANconfig open the Ethernet switch settings in the configuration area 'Interfaces' on the register 'LAN' with the button Ethernet Ports.
WEBconfig: LCOS menu tree / Setup / Interfaces / Ethernet-Ports.