@KirAsh4
I finally got it running. It turned out that the sync.- problem is well known since May 2016.

–> https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=149221

stopped the ntpd with :

sudo systemctl stop ntp

rather than running ntpdate, ran ntpdate-debian:

sudo ntpdate-debian

started ntpd

sudo systemctl start ntp

check

sudo ntpq -p

Now I´m happy!!