Tommi wrote (2022-01-30):

 FB>> Question is: How do I generate a config file for it, and where
 FB>> should it be located?

 TK>   jamnntpd -create /etc/jamnntpd.config

Debian/Ubuntu also has /etc/default/jamnntpd

IIRC you have to comment out the DAEMON_ARGS line or it will override the options in /etc/jamnntpd.config

---