Fedora update generates the error 23

Hello, when trying to update fedora 30 to fedora 31 or 32 or 33 the error Curl error (23) is displayed. I have found: for me setting fastestmirror=false in dnf.conf did the trick, if I’ve got error execute dnf clean all or retry and problem solved whithout touch zchunk that was introducing in :fedora: 30 to reduce the compression and performance in dnf .
But how do I set fastestmirror=false. Please write down each step because I am still a beginner.