He does use wifi at home. Is there a guide anywhere about setting the router? Right now he is on a business trip though. He's searched for two things I've confronted him about before. I wish I could see the sites he's visiting.
The settings you need to use will depend on what router you have. First you will need to set a static IP address for his phone. You should easily be able to do that in any router. Then you will set the router to collect the website information for that IP. How you do that will depend on the router you have, Google will tell you.
But remember, that will only give you the hits when he is on the wifi network. If he is using cellular data, that will not be stored on your router. That is why I suggested you install spyware. Any reason why that would not work?