change order of images attached to post

Answer Version 2

I apologize for the confusion.

Here’s how you can use the usort() function to sort the images (in the div#pic-con on the front-end):

<div id="pic-con">
<?php
    if (!empty($vid_pix)) {
        usort( $vid_pix, function( $a, $b ){
            $aPor = (int) get_post_meta( $a, 'photo_order', true );
            $bPor = (int) get_post_meta( $b, 'photo_order', true );

            if ( $aPor === $bPor ) {
                return 0;
            }

            return ( $aPor < $bPor ) ? -1 : 1;
        } );

        foreach ($vid_pix as $vP) {
            // echo `div.photo-upload-box` here
        }
    }
?>
</div>