modified /var/etc/mpd.conf, and set a more generous timing when MPD determines LCP echo timeout.
set link keep-alive 30 300
(it was: set link keep-alive 10 60)
I didn´t loose the connection for more than 24 hours now - which is a record!
I would wish pfSense had a feature under PPPoE, where it is possible to set those values.
Thanks to anyone who participated to this thread.
/gbosco