I lost my ability to share folders on my LAN?

Okay, this is odd. I'll leave this here, for future reference.

I've been working on this with three computers for ~ 1 hour. After posting this, my network suddenly shows all the computers and all their shared folders.

The mystery continues, but now it all works. Shrug.

Folks,

Looking for an assist. I have several ethernet connected computers, set up with a switch, and that goes to my router.

At some point in the last several weeks, my network stopped allowing each machine to see the other.

Attached is an image of the Network folder from one of my machines. It can see another one (cyclops) as a media streaming device. It cannot see a different machine.



I've gone through all the steps in the excellent tutorial, here: Share Files and Folders Over a Network in Windows 10

Nothing changes. Each machine is unable to see any other. Each machine has great internet access.

Where do I go from here?

Thanks!
Ken