smart home monitor can't find devices

[Nil]

Hello,

Before I did a whole reset of my modem and my computer, I had my Mac and  iPhone both  connected to the modem. At that time, the smart home monitor was finding only the device it was searching from and the modem. For example, using my computer, it was finding only my computer and the modem.

After I did a reset for both the modem and the computer, it is not finding anything even though I refreshed it and it acknowledges my network. 

I have pretty much all the security setting setup on both my modem and the computer. And I'm wondering could anyone of these be the reason? 

My question is: What could be the reasons of Smart Home Monitor not finding and listing the devices?

Can I please get a list of possible reasons, and hopefully solutions ?