Hello both and thanks for your kind replies. Apologies for the late answer but I have been kind of busy today.
Well, I tried to install security-misc on a private relay I am running for testing purposes. After the reboot when I tried to become root (using ‘su’) with my normal user. Unfortunately the system said “User not authorized” (or something like that, I do not remember exactly). Not sure why this happened.
Also, since my normal user was not in the sudoers list I was not able to become root AT ALL 
Not a great problem, I just reinstalled from scratch the system. For now, I think that I will just copy and paste the kernel parameters in /etc/sysctl.d, testing them line by line. Not very comfortable, but it is better than reinstall my system one more time.
Thanks for your answers.