How to setup Readynas rsync backup to pull from Ubuntu desktop

Been working on this for much longer than it should take.

I am trying to create a backup job on my ReadyNAS Pro 6 (6.10.6) using Rsync Server.

The source host is a PC running Ubuntu 20.04 desktop. Destination is a folder on the ReadyNAS Pro 6.

Rsync 3.1.3 is installed on the Ubuntu PC.

In the 'New Backup Job dialog:

On the left I select Remote

Protocol: remote: Rsync Server

Host: p710.local (or 192.168.0.40)

Port: 873

Share: have tried many

Login: valid user name(s)

Password: verified password(s)

If I click on the Browse button next to the Share: box a dialog box opens with no folders listed. I can click on the Connect As button and try other user names, including root, but no folders are displayed from which I can select. All I can do is click on cancel to close the dialog.

If I leave the Share: box empty and click on Test Connection, the Share: box name turns red.

If I put any folder name in Share: box and complete the destination side of the backup job I can click Next and fill in the backup schedule and save the backup job. If I try to run the job it fails with 'Connection can not be established.'

If I try to modify the backup job using settings, under the Source tab for the ReadyNAS backup job I have this:

Type: remote

Name: remote: Rsync Server

Host: P710.local (or 192.168.0.40)

Port: 873

Path: I have tried many

Login: valid user name(s)

Password: verified password(s)

So, if I leave the Path: box empty and click on Test Connection, I get "successfully connected to p710.local::", but I can't 'Apply' those changes to the backup job if the source Path: box is empty.

If I put anything in the Path: box and click on Test Connection, I get " Unable to connect to remote folder. Invalid network name or permission denied. Code: 7077010012". Even with this error I can click on the 'Apply' button and save the backup job.

The 'Browse' button beside the Path: box is greyed out and can't be clicked on (nothing happens) so I can't even see what or where the backup job is looking to show me a valid path name to select.

Not sure what els to try here.

I have set up several backup jobs just like this to pull backups via Rsync from my Synology NAS, so I am geussing that there is a setup issue on the Ubuntu desktop causing the difficulties.

Hoping someone here has run into this and figured out a solution.