Dear all,
Solution:
I was looking at the MPD website and the manuals. I found a solution to the issue of not being able to generate playlists from other clients than Rune Audio.
I added the following line to the mpd.conf:
playlist_directory "/srv/http/data/playlists"
Not sure it helped but I also made the directory read and write for all via the terminal with the following command.
chmod a+rw /srv/http/data/playlists -R
The playlists are then still not visible in clients. I converted them manually as I had issues with the plugin proposed with the following steps:
In RuneAudio load a Playlist
Save that loaded playlist in for example Ymuse.
It creates a file with m3u extension in the directory above.
I deleted the playlists without extension in RuneAudio
The generated playlists work in all clients.
Hope this helps people with similar issues.
John