Problem with pagination link (error 404)

I have something here that I used on the website of a real estate agency

You’re already using Bootstrap. But, take a look https://getbootstrap.com/docs/4.0/components/pagination/

In your code, a line before var $actualPagina = get_query_var…
Add:

global $actualPagina;

So here’s what you do…

Replace

<?php get_template_part ( 'paginacion_prop' );?> 

by

<?php thomas_pagination($propiedades->max_num_pages);?>

In your functions.php enter the following code:

<?php
if( !function_exists('thomas_pagination') ): 
    function thomas_pagination($pages="", $range = 2) {
        $showitems = ($range * 2)+1;

        global $actualPagina;
        if(empty($actualPagina)) $actualPagina = 1;

        if($pages == '') {
            global $wp_query;
            $pages = $wp_query->max_num_pages;
            if(!$pages)
            {
                $pages = 1;
            }
        }

        if(1 != $pages) {
            echo '<ul class="pagination">';
            if($actualPagina > 2 && $actualPagina > $range+1 && $showitems < $pages) echo '<li><a href="' . esc_url(get_pagenum_link(1)) . '"><span class="fa fa-angle-double-left"></span></a></li>';
            if($actualPagina > 1 && $showitems < $pages) echo '<li><a href="' . esc_url(get_pagenum_link($actualPagina - 1)) . '"><span class="fa fa-angle-left"></span></a></li>';

            for ($i = 1; $i <= $pages; $i++) {
                if (1 != $pages &&( !($i >= $actualPagina + $range + 1 || $i <= $actualPagina - $range - 1) || $pages <= $showitems )) {
                    echo ($actualPagina == $i)? '<li class="active"><a href="#">' . esc_html($i) . '</a></li>' : '<li><a href="' . esc_url(get_pagenum_link($i)) . '">' . esc_html($i) . '</a></li>';
                }
            }

            if ($actualPagina < $pages && $showitems < $pages) echo '<li><a href="' . esc_url(get_pagenum_link($actualPagina + 1)) . '" class="next"><span class="fa fa-angle-right"></span></a></li>';
            if ($actualPagina < $pages - 1 &&  $actualPagina + $range - 1 < $pages && $showitems < $pages) echo '<li><a href="' . esc_url(get_pagenum_link($pages)) . '"><span class="fa fa-angle-double-right"></span></a></li>';
            echo '</ul>';
        }
    }
endif;
?>