If you can only monitor yourself. It means WFilter can not see other computers internet traffic.
You can not monitor other computers internet usage in a network unless you have access to their network traffic.
There have two ways to see other computers internet traffic:
1. Configure a span port(port mirroring) in your switch.
How to check whether a switch supports port mirroring? 2. Do monitoring in the gateway or proxy.
If you already setup a computer as the gateway or proxy server, you just need to install WFilter in the server to do monitoring.
Since many networks are using a router as the gateway, using a port mirroring switch is a good choice. Port mirroring allows you to setup a port in the switch to receive packets of other ports. Setting up a mirror port does no change to your network topology, and it will not affect your network speed. A broadcasted hub can also help you to do monitoring, however, broadcasted hubs can only work in 10M bit mode, and it is not so stable. Therefore I recommend you not to use a broadcasted hub to do monitoring.
Check out WFilter deployment examples with several port mirroring switches:
WFilter deployment examples.
