When you download and install Network Probe it will support single-computer mode only, meaning only traffic sent from and received by the computer where Network Probe is installed will be monitored.
For full utilization of Network Probe you need to generate a license key from the application user interface. This will enable promiscuous mode and the probe will pick up all network traffic the network card sees, including traffic from to and from other hosts on the network. Make sure you install the probe on a computer with a network card capable of promiscuous-mode operation. If the card does not support promiscuous mode, a warning is shown on the login screen:
The computer should be connected to a mirrored port on your network switch, also known as a SPAN (Switched Port Analyzer) port. The normal operation of a switch is to send packets only to the computer they destinate to, but a SPAN port receives a copy of all packets going through the switch. A SPAN port is normally available on managed switches only.
It is also possible to use Network Probe on a wireless network, as long as the wireless NIC supports promiscuous mode.
You should install a copy of Network Probe on each subnet you want to monitor.