@zimowski @ajlanes Your server isn't polling for posts. The remote server sends them. It does this to all followers when someone makes the post.
What it's not going to do is go back and send every post that an account has made when you follow, because that would be spam.
Therefore, if you wish to comment on an old post, simply enter its URL in the search box. Your server will then go and get it, and you can reply or repost as you see fit.
This has been explained so very many times now that I'm starting to think what you're doing here is some sort of weird performance art.