All I needed to do was setting the permissions to 744 for the archive directory and the symlinks resolved correctly after a reboot of coturn

My turnserver installation on Debian runs as the user turnserver and not as root, nor is the user turnserver in any group owning the letsencrypt directory.
If your turnserver does run as root, it should be fine just adding execute permissions.

I hope this helps some of you.

Was zum Testen die Tage....