Every post on the Landing has its own access permissions so, if you are not logged in, are not a member of the relevant group, or are not being followed by the person sharing it (and that person has not shared it with people they follow), you will not be able to see things with restricted access that you have not been allowed to see. This is by design. There are many tens of thousands of posts on this site, but they are only visible to the people who have been explicitly allowed to see them. If you are not logged in, you will only see public posts. If you are logged in but not a member of any groups and not networked with other people, you will see public posts and those for logged in users. If you are a member of any groups, you will see posts for those groups. To see more, join more!