/etc/resolv.conf changes every booting time

["Jon Smart" <jon@daydaylive.us>]

Hello

I have removed the default systemd-resolved local dns service following
the link below,

https://askubuntu.com/questions/907246/how-to-disable-systemd-resolved-in-ubuntu

And I have unbound installed and enabled as local DNS server.

But every time I reboot the server, the configuration file
/etc/resolv.conf changes to a default one. So every time I have to update
its content to:

nameserver 127.0.0.1

(points to unbound)

How to stop the auto-changes to /etc/resolv.conf after rebooting?

Thanks.