Resolved: Linux guests unable to access Windows 10 guest?

[sam452]

This is really odd, it seems. I've set up on the Windows 10 guest a service on a special port.
My Mac Catalina accesses this service running on the Windows guest.

My Ubuntu 18, Ubuntu 16, Debian 9 are unable to ping the Windows 10 guest. At all.
My Windows 10 guest pings my Linux guests fine.
Even though the Mac host finds this Windows service, I checked the Win firewall. Most everything is "Allow".
I've changed the Networking on Linux and Windows guest from "Shared" to "Bridge" on the working interface. The same result occurs. No change.

I'm not running a firewall on the Linux guests. I've run curl mywindowsIPaddy and curl quits with no response.
I've checked my Parallels 15 desktop settings. They all relate to the Mac. But why does Windows access the Linux guests, but the Linux guests do not?

 

[sam452]

To further isolate variables, I booted up Mint on Parallels of my personal machine which would determine if my Parallels 15 is a factor. No change. Also attempted using a Raspberry Pi running Raspian on my LAN but no change, either.
Looking outside Parallels, it seems Windows 10 Home by default blocks traffic. I see in Win 10 that I am running a Private mode where I can disable the firewall for this testing.
What was throwing me was that the Mac host had no trouble accessing this Win 10 resource, which suggests Parallels is circumventing the default Windows network firewall/mode.