Turn off ntp outgoing to the internet

Hello everyone,
I have the following challenge:
I only set an internal NTP server on a SLES 15 SP3. This also works, but the NTP service also tries to access the Internet via NTP. I can check this on my external Firewall.
Is there a way to turn that off?

Many greetings

I’m not sure on SLES, but on RHEL-variants you can edit /etc/ntpd.conf or /etc/chrony.conf and comment out or edit the lines starting with server to change where your NTP daemon is looking (assuming you’re running ntpd or chronyd for NTP, if you have it set up to do something like run ntpdate every 5 min via cron then you’d look in your crontab or if using another NTP daemon then you’d look for its config via man).

Note that you may have >1 method set up for some odd reason because someone thought it was a good idea or packages automatically did it.