smbclient not finding share for localhost

[Frank Miles <pedicularis@mail.com>]

My home linux/Debian/buster machine has suddenly made samba 'shares' 
invisible to my Win7 virtual machine (running under kvm/qemu).

Using smbclient I get two different responses:

  smbclient -L localhost

only gives the error-message response:

  Unable to initialize messaging context
  Connection to localhost failed (Error NT_STATUS_UNSUCCESSFUL)

But if I given the IP address:
   smbclient -L 192.168.1.20
it asks for a password, then tells me about the shares:
  Unable to initialize messaging context
  Enter WORKGROUP\user's password:
   ...shares...
   server info
   workgroup info

If I do the same thing on another computer (running Stretch), I
don't get the messaging-context whining, and after entering my
password get the information whether I've given it 'localhost'
or the IP address as an argument.  Unfortunately the sambas
are a different version, so I don't think I can directly compare
their configuration.  In case you wonder, testparm's [global]
output is:
[global]
        bind interfaces only = Yes
        deadtime = 1440
        dns proxy = No
        domain master = Yes
        interfaces = br0 eth0 127.0.0.0/8
        keepalive = 5
        log file = /var/log/samba/log.%m
        map to guest = Bad User
        max log size = 1000
        name resolve order = wins lmhosts bcast
        obey pam restrictions = Yes
        pam password change = Yes
        panic action = /usr/share/samba/panic-action %d
        passwd chat = *Enter\snew\s*\spassword:* %n\n 
*Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .
        passwd program = /usr/bin/passwd %u
        server role = standalone server
        unix password sync = Yes
        username map = /etc/samba/username.map
        usershare allow guests = Yes
        wins server = 192.168.1.20
        idmap config * : backend = tdb
        hosts allow = 192.168.0.0/16 127.0.0.1
        hosts deny = ALL

Any hints or pointers to the Fine Manual gratefully received!
   -Frank
{AFAICR I hadn't changed smb.conf since when it had been working.
And I've tried this with the firewall completely off}