I tried to get the next and previous URL, and create a navigation. But it seems to only retrieve the permalink from the two first posts (but not the others recents posts).

I have 5 posts (ID = 25, 86, 80, 75, 45). When I am on the first post (ID = 25) and I click on previous post, I am going to post ID = 45, and after when I click on previous it stay on the same page.

    <?php 
      if (have_posts()) : while (have_posts()) : the_post();
    
      $prev = get_permalink(get_adjacent_post(false,'',false));
      $next = get_permalink(get_adjacent_post(false,'',true)); ?>
    
      <li class="post-link">
        <a class="prev" href="<?php echo $prev; ?>">
          <span class="icon-prev"></span>
        </a>
      </li>
      
      <li class="post-link">
        <a class="next" href="<?php echo $next; ?>">
          <span class="icon-next"></span>
        </a>
      </li>
    
    <?php endwhile; endif; get_footer(); ?>

I also tried to put the code after the while loop.