Verify that it's the crappy SystemD attempt at an NTP daemon that is hogging the port/
Lines with "#" starting are commands to be run as root, either by "sudo bash" to get an escalated-privilege shell, or by logging in as root on the Pi. (don't type the "# " at the start of the line..)
Check to see what process is open on port 123 (extra grep is to filter out the grep command as that will show up otherwise):
# netstat -planet | grep- v grep | grep :123
Check the status of the systemd attempt at an NTP daemon, see if it's running:
# systemctl status systemd-timesyncd
I would always suggest running a real NTP server instead of a systemd service - that goes across the board no matter what the service is. The reasons are many, but I don't really want to get into that kind of a religious discussion on here ;)
Stop the systemd time daemon:
# systemctl disable systemd-timesyncd
Now it should be possible to start the real ntp server, verify that it's running, then after a while, verifiy the current state of NTP's performance
# service ntp start
# service ntp status
After a while, run this and see if it makes sense:
# ntpq -p
Hopefully this helps..
Cathal Ferris (EI4IWB)
Two standard KiwiSDRs listening to 14 bands of WSPR from an outdoor AAA-1d