It all started by having no results in Synology Download Station.
Thanks to the Synology forum I was able to open and edit the DLM files (Synology forum topic).
Updating the Download Station search engines (DLM files) in Download Station gave me the expected results.
All plugins on this site will work with a public source (no username, no password).
I definitely do not know all torrent sources, feel free to submit your favorite torrent source on the contact page.
Before contacting me, please read the Synology Download Station forum.