Portfolio navigation through same category for The7 -Mulltipurpose wordpress them

functions.php

if ( ! function_exists( 'presscore_post_navigation' ) ) :
 
	/**
	 * Next/previous post buttons helper.
	 *
	 * Works only in the loop. Sample options array:
	 * array(
	 *		'wrap'				=> '<div class="paginator-r inner-navig">%LINKS%</div>',
	 *		'title_wrap'		=> '<span class="pagin-info">%TITLE%</span>',
	 *		'no_link_next'		=> '<a href="#" class="prev no-act" onclick="return false;"></a>',
	 *		'no_link_prev'		=> '<a href="#" class="next no-act" onclick="return false;"></a>',
	 *		'title'				=> 'Post %CURRENT% of %MAX%',
	 *		'next_post_class'	=> 'prev',
	 *		'prev_post_class'	=> 'next',
	 *		 next_post_text'	=> '',
	 *		'prev_post_text'	=> '',
	 *		'echo'				=> true
	 * )
	 *
	 * @param array $args Options array.
	 * @since presscore 1.0
	 */
	function presscore_post_navigation( $args = array() ) {
		global $wpdb, $post;
 
		if ( !in_the_loop() ) {
			return false;
		}
 
		$next_post_text = _x('Prev', 'post nav', LANGUAGE_ZONE);
		$prev_post_text = _x('Next', 'post nav', LANGUAGE_ZONE);
 
		$defaults = array(
			'wrap'				=> '<div class="navigation-inner">%LINKS%</div>',
			'title_wrap'		=> '',
			'no_link_next'		=> '<a class="prev-post disabled" href="javascript: void(0);">' . $next_post_text . '</a>',
			'no_link_prev'		=> '<a class="next-post disabled" href="javascript: void(0);">' . $prev_post_text . '</a>',
			'title'				=> '',
			'next_post_class'	=> 'prev-post',
			'prev_post_class'	=> 'next-post',
			'next_post_text'	=> $next_post_text,
			'prev_post_text'	=> $prev_post_text,
			'echo'				=> true
		);
		$args = apply_filters( 'presscore_post_navigation-args', wp_parse_args( $args, $defaults ) );
		$args = wp_parse_args( $args, $defaults );
 
		$title = $args['title'];
 
		if ( false !== strpos( $title, '%CURRENT%' ) || false !== strpos( $title, '%MAX%' ) ) {
 
			$posts = new WP_Query( array(
				'no_found_rows'		=> true,
				'fields'			=> 'ids',
				'posts_per_page'	=> -1,
				'post_type'			=> get_post_type(),
				'post_status'		=> 'publish',
				'orderby'			=> 'date',
				'order'				=> 'DESC'
			) );
 
			$current = 1;
			foreach( $posts->posts as $index=>$post_id ) {
				if ( $post_id == get_the_ID() ) {
					$current = $index + 1;
					break;
				}
			}
 
			$title = str_replace( array( '%CURRENT%', '%MAX%' ), array( $current, count( $posts->posts ) ), $title );
		}
 
		$output = '';
 
		$output .= str_replace( array( '%TITLE%' ), array( $title ), $args['title_wrap'] );
 
		// next link
		if ( 'dt_portfolio' == get_post_type() ) {
			$next_post_link = get_next_post_link( '%link', $next_post_text, TRUE, ' ', 'dt_portfolio_category' );
		}
		else {
			$next_post_link = get_next_post_link( '%link', $args['next_post_text'] );
		}
		if ( $next_post_link ) {
			$next_post_link = str_replace( 'href=', 'class="'. $args['next_post_class']. '" href=', $next_post_link );
		} else {
			$next_post_link = $args['no_link_next'];
		}
 
		// previos link
		if ( 'dt_portfolio' == get_post_type() ) {
			$previous_post_link = get_previous_post_link( '%link', $prev_post_text, TRUE, ' ', 'dt_portfolio_category' );
		}
		else {
			$previous_post_link = get_previous_post_link( '%link', $args['prev_post_text'] );
		}
		if ( $previous_post_link ) {
			$previous_post_link = str_replace( 'href=', 'class="'. $args['prev_post_class']. '" href=', $previous_post_link );
		} else {
			$previous_post_link = $args['no_link_prev'];
		}
 
		$output = str_replace( array( '%LINKS%', '%NEXT_POST_LINK%', '%PREV_POST_LINK%' ), array( $next_post_link . $previous_post_link, $next_post_link, $previous_post_link ), $args['wrap'] );
 
		if ( $args['echo'] ) {
			echo $output;
		}
 
		return $output;
	}
 
endif;

past this code in your theme/child theme's functions.php and your portfolio prev next will navigate through the same category.