Hi Jesko,

This is a customization question and support doesn't offer customization services as we wrote on our support homepage and on this area. I will try to help you this time though

Yes that is possible, to do that you should add this code in functions.php

add_filter( 'portfolioposttype_args', function ( $args ) {
    $args['rewrite'] = [
        'slug'       => 'portfolio/%portfolio_tag%',
        'with_front' => true,
    ];
    return $args;
} );
add_filter( 'post_type_link', function ( $post_link, $post ) {
    if ( is_object( $post ) && $post->post_type == 'portfolio' ) {
        $terms = wp_get_object_terms( $post->ID, 'portfolio_tag' );
        if ( $terms ) {
            return str_replace( '%portfolio_tag%', $terms[0]->slug, $post_link );
        }
    }
    return $post_link;
}, 10, 2 );

After this, go to Settings > Permalinks and just click Save Changes to flush permalinks. After that you will be able to see the permalink structure of /portfolio/tag/post-title

Hi Jesko,

I am glad that it worked for you! 

Sure you can prevent this behavior of WordPress by disabling the unique post slug check for "portfolio" post type:

function custom_prevent_portfolio_duplicate_slug( $slug, $post_id, $post_status, $post_type, $post_parent, $original_slug ) {
    if ( 'portfolio' === $post_type ) {
        return $original_slug;
    }
    
    return $slug;
}
add_filter( 'wp_unique_post_slug', 'custom_prevent_portfolio_duplicate_slug', 10, 6 );

Hi Jesko,

Sorry for the delay as I was not able to provide support for customers.

Can you please tell me what exactly is the problem, because I do not understand the content of each portfolio item is showing in one page. It would help me if you provide your WP credentials so I can test directly on your site my solution.

To include your credentials click Insert Credentials button in editor toolbar. (See how)

Hi Jesko,

This pertains to customization, and our support team does not provide customization services, as stated on our support homepage and in this section. However, I'll do my best to assist you this last time.

I've added the following code snippet that will distinguish the requested portfolio ID, since the WordPress behavior returns one or more posts depending on the matched items:

// Differentiate the portfolio items by their portfolio_tag taxonomy
add_filter( 'request', function( $query_vars ) {
    $portfolio_slug = kalium_get_array_key( $query_vars, 'portfolio' );
    $portfolio_tag = kalium_get_array_key( $query_vars, 'portfolio_tag' );
    
    if ( ! empty( $portfolio_slug ) && ! empty( $portfolio_tag ) ) {
        $posts = get_posts( [ 
            'post_type' => 'portfolio', 
            'portfolio_tag' => $portfolio_tag,
            'posts_per_page' => -1,
        ] );
        
        foreach ( $posts as $post ) {
            if ( $post->post_name === $portfolio_slug ) {
                $post_id = $post->ID;
            }
        }
        
        if ( isset( $post_id ) ) {
    
            unset( $query_vars['portfolio'] );
            unset( $query_vars['portfolio_tag'] );
            unset( $query_vars['name'] );
            $query_vars['p'] = $post_id;
        }
    }
    
    return $query_vars;
} );

Now after this, you see that these portfolio items are separated:

Post 1

(view large image)

Post 2

(view large image)

Hi Jesko,

You are welcome, always. I am sorry but I cannot take any custom work apart from Laborator, however feel free to ask questions and if I cannot help you, then I could recommend adequate people for you. Simply open a ticket here or drop an email in our contact form requesting for my help.

Thank you for your understanding. 

If you have a spare moment, I kindly request that you consider sharing your positive experience with us on G2 because we are trying to push Kalium outside of ThemeForest and we need your help. Your review would not only make our day but also help other potential customers to make an informed decision about choosing our theme for their needs.