This as well as the article you've linked is a little misleading. NTDS Replication Connections are not the same thing as Site Links. Site links need the first bit set, whereas Replication Connections need the 4th bit set (only if they are not AutoGenerated). You need to incorporate the setting of this bit with the other values that may already be present.
@ErnestoMayol-4634 , no a public IP is not required.