<?php
/*
 * 1. Go to Settings > Permalinks and select any page as home page
 * Then use the following code
 *
 * You can add those codes in your functions.php in the theme, if you think your theme won’t be changed.
 * Otherwise mu-plugins is the best solution. To use mu-plugins, go to /wp-content/ and find the folder with name 'mu-plugins'.
 * If there is no folder in that name, then create a folder, name it 'mu-plugins', create a file inside that,
 * give any name you like and paste the code in there. You don't need to activate that plugin. Mu-plugins means must use plugins,
 * so it will be activated automatically always. If you use mu-plugins then add a php start tag at the beginning of the code.
 *
 * Just change the correct CPT name
 */

add_action("pre_get_posts", "custom_front_page");
function custom_front_page($wp_query){
    if(is_admin()) return;

    if($wp_query->get('page_id') == get_option('page_on_front')){

        $wp_query->set('post_type', 'CUSTOM POST TYPE NAME HERE');
        $wp_query->set('page_id', ''); //Empty

        $wp_query->is_page = 0;
        $wp_query->is_singular = 0;
        $wp_query->is_post_type_archive = 1;
        $wp_query->is_archive = 1;
    }
}