I think he's saying that he'd like to spy on every communication sent from his home by somehow monitoring traffic from his IP address. That way he wouldn't have to tamper with individual devices.
Most routers can be used to collect traffic information by enabling the 'log' setting in administration. However, this is not going to provide much useful information as it will only show the destination url and the port number for each local IP address.
You can also set the router to give a device a static IP address so that (for instance) you will always know that communications from 192.168.1.50 are from WW's iPhone.
For any given IP address on your network, you can see the websites visited and port (those tell you the protocol used). For example port 80 is a regular website visit.
Texts will not show at all as they run only over the cellular connection.
Emails will show only the url of your email server, outgoing ports are 25/26 and incoming is 110. The headers (containing the details of final destination) are not going to appear. However, you will be able to see the frequency of requests (not traffic).
Same problem for IMs. Details of who WW communicates with will not be able to be collected this way.
So this could be useful for detecting a secret email account, not sure it will do much else.