PC MAC sharing on network

I have my own router to which my PC (win10 pro) and my MAC (El Cap) are connected via WIFI. The router is connected on the WAN-side to another home WIFI network (my landlord’s). I’m trying to get my mac and pc to be visible to each other but, while I had momentary access a couple of months ago, they cannot see each other presently. Anyone have any ideas? I have, I think, followed correctly the basic steps for such interworking. Perhaps adding my own router means I need to do something unusual to get things working?? my router is providing DHCP. Thanks for any ideas.