In order for NTOP running on OnPlus to see all LAN traffic, it requires either a netflow-capable router (which would feed the data to the ON100 via the ON100's LAN port/IP), or it requires a switch that has the ability to port mirror all traffic passing through it to be placed before the WAN router and mirror that traffic to the ON100 (via the ON100's MON port).
While not supported (or even recommended), another possiblity depending on the LAN configuration could be to place a dumb 'hub' between the WAN router and the switch (that lacks port mirroring capability) to which all LAN traffic is connected, and to connect the ON100's MON port to this hub so that it is able to also see all the traffic flowing through the hub. There are also ethernet 'tap' devices or cables that could be used with similar effect.
If the LAN traffic connects directly into ethernet ports on the WAN router, and that router doesn't support mirroring of that traffic, the only other alternative might be to configure the above hub or ethernet tap on the WAN side of the router. You would lose visibility of the internal network traffic, but NTOP would be able to account for all WAN traffic at the least.
Of course my recommendation would be to upgrade the LAN to a head-end switch that supports port mirroring
Article ID:4018 Monitor Web Services on a Device on Cisco OnPlus Portal
Objective Event Monitors are mainly used to monitor the device in order
to provide notifications to the technicians in a timely manner if there
are any problems with the device perfor...
Article ID:3884 Monitor Duplicate IP on OnPlus100 Objective The
Duplicate IP monitor is one of the event monitors on the OnPlus100
device to check the network performance. Duplicate IP monitor checks
whether more than one device in the network uses the sa...
Article ID:3986 Monitor Host Performance with Internet Contol Message
Protocol (ICMP) for a Device on Cisco OnPlus Portal Objective Event
Monitors are mainly used to monitor the device in order to provide
notifications to the technicians in a timely manne...