Custom Pagination for Posts not working after page 11 - php

Question

I have created a section on home where i am showing 6 post starting from offset 3 and below that i add a custom pagination code.
I have total 93 published post and as i set offset 3 so the pagination is set for rest 90 posts.
For 90 posts, total number of links is 15 in pagination.
Pagination works fine till 11 page i.e mysiteurl/page/11. when i click 12 in the pagination links, it show me 404. It should show me next 6 posts.
Here is my code:
<?php
// function to get page number
function get_url_var($name){
$strURL = $_SERVER['REQUEST_URI'];
$arrVals = split("/",$strURL);
$found = 0;
foreach ($arrVals as $index => $value){
if($value == $name) $found = $index;
}
$place = $found + 1;
return $arrVals[$place];
}
function myprefix_query_offset(&$query) {
//Before anything else, make sure this is the right query...
if ( ! $query->is_home() ) {
return;
}
//First, define your desired offset...
$offset = 3;
//Next, determine how many posts per page you want (we'll use WordPress's settings)
$ppp = 6;
$page = get_url_var('page');
//Next, detect and handle pagination...
if ( $page ) {
//Manually determine page query offset (offset + current page (minus one) x posts per page)
$page_offset = $offset + ( ($page-1) * $ppp );
//Apply adjust page offset
$query->set('offset', $page_offset );
}
else {
//This is the first page. Just use the offset...
$query->set('offset',$offset);
}
}
add_action('pre_get_posts', 'myprefix_query_offset', 1 );
function myprefix_adjust_offset_pagination($found_posts, $query) {
//Define our offset again...
$offset = 3;
//Ensure we're modifying the right query object...
if ( $query->is_home() ) {
//Reduce WordPress's found_posts count by the offset...
return $found_posts - $offset;
}
return $found_posts;
}
add_filter('found_posts', 'myprefix_adjust_offset_pagination', 1, 2 );
$page = get_url_var('page');
$paged = ( $page ) ? $page : 1;
if($paged == 1){
$custom_args = array(
'post_type' => 'post',
'posts_per_page' => 6,
'paged' => $paged,
'offset' => 3,
'post_status' => 'publish'
);
}else{
$custom_args = array(
'post_type' => 'post',
'posts_per_page' => 6,
'paged' => $paged,
'offset' => 3 + ( ($paged-1) * 6),
'post_status' => 'publish'
);
}
$wpb_ll_query = new WP_Query( $custom_args );
if ( $wpb_ll_query->have_posts() ) : while ( $wpb_ll_query->have_posts() ) : $wpb_ll_query->the_post();
?>
<div class="col-lg-4 col-sm-6 col-md-4 col-xs-6 rec-first1">
<a href="
<?php the_permalink();?>">
<div class="grid-latest-posts">
<?php
if(has_post_thumbnail())
{
the_post_thumbnail();
}
else
{
?>
<img class="no-image" src="/wp-content/uploads/2017/02/no-image.png">
<?php
}
$category_object = get_the_category(get_the_ID());
$category_name = $category_object[0]->name;
?>
<label><?php echo $category_name;?></label>
</div>
</a>
<div class="style-txt-nxt">
<span> <a href="<?php the_permalink();?>">
<?php
$string = get_the_title();
$post_title = (strlen($string) > 30) ? substr($string,0,30)."..." : $string;
?>
<?php
echo $post_title;
?>
</a></span>
<p id="art-date2">
<?php echo get_the_date(); ?></p>
<div class="line1">
</div>
<h3>
<a href="
<?php the_permalink();?>">read more</a>
</h3>
</div>
</div>
<?php
endwhile;
//wp_reset_postdata();
else : ?>
<p>
<?php _e( 'Sorry, no posts matched your criteria.' ); ?></p>
<?php endif; ?>
</div>
</div>
</section>
<!-- Pagination for posts -->
<section>
<div class="container">
<div class="row">
<div class="col-lg-12 col-md-12 col-sm-12 col-xs-12">
<!--<h3><a id="more_posts">Load More</a></h3>-->
<?php
if (function_exists(custom_pagination)) {
custom_pagination($wpb_ll_query->max_num_pages,"",$paged);
}
wp_reset_postdata();
?>
</div>
</div>
</div>
</section>
I defined custom_pagination() function in function.php
<?php
function custom_pagination($numpages = '', $pagerange = '', $paged='') {
if (empty($pagerange)) {
$pagerange = 2;
}
/**
* This first part of our function is a fallback
* for custom pagination inside a regular loop that
* uses the global $paged and global $wp_query variables.
*
* It's good because we can now override default pagination
* in our theme, and use this function in default queries
* and custom queries.
*/
global $paged;
if (empty($paged)) {
$paged = 1;
}
if ($numpages == '') {
global $wp_query;
$numpages = $wp_query->max_num_pages;
if(!$numpages) {
$numpages = 1;
}
}
/**
* We construct the pagination arguments to enter into our paginate_links
* function.
*/
$pagination_args = array(
'base' => get_pagenum_link(1) . '%_%',
'format' => 'page/%#%',
'total' => $numpages,
'current' => $paged,
'show_all' => False,
'end_size' => 1,
'mid_size' => $pagerange,
'prev_next' => True,
'prev_text' => __('«'),
'next_text' => __('»'),
'type' => 'plain',
'add_args' => false,
'add_fragment' => ''
);
$paginate_links = paginate_links($pagination_args);
if ($paginate_links) {
echo "<nav class='custom-pagination'>";
echo "<span class='page-numbers page-num'>Page " . $paged . " of " . $numpages . "</span> ";
echo $paginate_links;
echo "</nav>";
}
}?>
Can anyone suggest me some solution to fix it.