How to setup local (private) node and server

I’ve discovered the [nodes] section within the rpt.conf file. This seems like where I’d set up my list of nodes that are connected to each other on my local network.

But I’m confused by much. Do I need to setup this config file on every node? Does every node have a list of all other nodes? Or do I only list my local nodes on my first node (the ‘server’?)

Also, when I run allmon2, I get some errors that make me think I’m still missing some basic setup.
Screenshot from 2021-11-24 09-00-24