FFS can't move files to trash

[no1dmfan]

Hi,
I'm syncing files from my Macbook (MacOS Catalina) to a Synology Diskstation and a LaCie external HDD.
Data copying works fine but when FFS wants to move an older file to trash to replace it with a newer version it fails. The error messages are slightly different but seem to show the same problem.
With LaCie: OSStatus -5000 Insufficient access privileges for operation. [FSMoveObjectToTrash]
With Diskstation: File … cannot be deleted. EPERM: Operation not permitted [unlink]
It has worked perfectly in the past so what can I do to get this running again?
FFS has full rights to access HDD, copying file system permissions is disabled in settings.
Thanks for your help!!

[no1dmfan]

I have solved the problem – there were files on both Diskstation and LaCie that were locked. I have unlocked them all and now it works fine.