Kubuntu file sharing

[rikona]

New comp box with Kubuntu [Nice!]. Problem(s) with Kubuntu file sharing
with Win7. Shared a folder using properties in Dolphin, but Win7 can't
see the comp at all. And Kubuntu can't see the Win7 box. But iMac can
see both Win7 & Kubuntu - boxes & files, so it seems to be sort of
working. Old Ubuntu 16 box worked fine with Win7.

Tried 
https://masonbee.nz/simple-samba-file-sharing-set-up-for-kubuntu-20-04/
Didn't work re Kubuntu & Win7 - iMac sees the additional test shares I
set up in smb.conf but fails when trying to see THOSE files & closes
finder .

https://wiki.kubuntu.org/KubuntuFilesharing
says "Rip out the current Samba sharing UI in KDE, it's broken."
and "For SMB support, Samba would need to be installed." which I did in
the above.

Other sites use the IP address - is this necessary? Should I set Kubuntu
to have a fixed IP address [the old Ubuntu did]? I usually do this with
things on my lan.

How can I get Kubuntu & Win7 to work together - both seeing the box and
using the files in each?