[Xubuntu] samba install, browse issues on linux machines

Three workstations on a LAN.

One is Windows 7, in a workgroup

Two are Xubuntu 18.04.1 LTS, each running:
--Samba 2:4.3.11 + dfsg-0ubuntu 2:4.3.11 + dfsg-0ubuntu
--smbclient 2:4.3.11 +dfsg-0ubuntu 2:4.3.11+dfsg-0ubuntu


The Windows 7 machine can see and access the shared directories of both Xubuntu machines. Neither Xubuntu machine can see the Win7 machine nor the other Xubuntu node.

-0-

The HOSTS file of each machine asserts the static IP addresses and aliases of the two other machines.

Firewalls on each machine are set to allow SMB inward with no restrictions outward.

One Xubuntu machine has Thunar v1.6.11. The other has Thunar v1.6.15. Regardless of version, Thunar behaves the same:

Thunar, when side pane displays "tree," Network does not appear.

If side pane is set to display "shortcuts," there is a Network listing, and below it "Browse Network." When one clicks "Browse Network," this message presents:

Failed to open "/ on".
The specified location is not supported.

I've been at this a number of hours today. I no longer can see the forest for the trees, and am pre-embarrassed that I have overlooked something very fundamental.

Would someone kindly set me right?

Thank you in advance,

Bob