The IP Traffic/Real-Time page displays real-time bandwidth being used on selected network IP addresses/ranges. It does not collect bandwidth usage based on a specific Tomato interface. That is the purpose of the Bandwidth/Real-Time function.
IPs currently on graphic: allows you to select from which IP addresses/ranges you want to display bandwidth data.
Hidden Addresses: On this menu, you can select IP addresses whose bandwidth is currently not being displayed on the graph to be measured/graphed.
The graph has a 10-minute window, with a 2-second interval. That means it displays a maximum of 10 minutes of bandwidth data which is refreshed a maximum of every 2 seconds.
RX numbers show incoming bandwidth (to the LAN).
TX numbers show outgoing bandwidth (to the WAN).