Wastebasket not enabled for NFS mounted folders

I have been unable to find a relevant answer to this problem, although it's the sort of thing that is commonly reported on the web.

I recently migrated my existing HDD drives to a new Synology NAS after the old one died, which is when my troubles started.

I have always mounted a number of folders from the NAS on my Ubuntu PC using NFS, so that I can create "backup" copies of important files on the server. Before my old NAS died I used FreeFileSync to mirror files and folders from Ubuntu to the NFS-mounted NAS folders, and this worked fine. Since the migration I have been unable to do this because the NFS-mounted folders apparently cannot see a trash/rubbish bin/wastebasket to move the updated or deleted files to. I get the dreaded "Unable to find or create Rubbish Bin directory... " message. I'm fairly sure that I need to create an appropriate ".Trash" folder with its usual subfolders in the Synology Shared Folders, but I can't discover how to do it.

I mount the NAS folders (successfully) using /etc/fstab, e.g.

192.xxx.x.xxx:/volume1/videos /media/NAS/NAS\040videos nfs timeo=200,fg

During the migration of my HDD drives I did have problems with some presumably pre-existing .Trash folders turning up in my Ubuntu wastebasket as links which meant that I had to delete stuff from the NAS before I could empty the wastebasket. "Something" obviously went wrong during the migration but I can't find what, or how to fix it.

I can delete files manually from the mounted folders, and I can recycle files from the NAS folders if I login to the to NAS.