Error 404 when trying to reach a link

Hello, i ve been uploading my site online.
I do have access to my home page, but the login link is sending me back a 404 error.
Everything was working fine on my local server, but i can't access my links online since. As i am not using routes.php, the link is as simple as this <a class="btn btn-outline-info" href="<?= base_url('Auth'); ?>">Login</a>.


Could you please help me.
David