Redirect single page

I am trying to redirect my front page for mobile users.
my pc users see one page and my mobile users see a different one.

I have already done this part to the function folder of the plugin
but now it isnt detection mobile devices

replace

add_action(‘init’, ‘pmr_mobile_redirect’);

with

function pmr_single_page_only(){

if (is_page(42)){

pmr_mobile_redirect();

}
}

add_action(‘get_header’,’pmr_single_page_only’);

https://wordpress.org/plugins/php-mobile-redirect/