failed to retrieve share list from server connection refused ubuntu 18.04

How to Save: To save in nano use “CTRL-O”, then “CTRL-X”.

Tip: Replacing sudo nano with gksudo gedit gives you a nice graphical editor.

And check the following lines. Change workgroup name as same in the network

if still problem exist try restart the computer and try. Still not working?

and add computer ip address and name in hosts file. Save and exit.

Sample ip and name:

and then restart the servers with service smbd restart and service nmbd restart

https://help.ubuntu.com/community/Samba/SambaServerGuide