Why cookies are not set via setcookie in php?

Question

PHP

FE - admin.site.ru
BE - site.ru

FE accesses site.ru/v1/auth/login
BE tries to set the cookie via setcookie :

$time = time();
      $exp = $time + (60 * 60 * 24 * 30);

      setcookie('token', '111111', $exp, '/', '.site.ru');

• In Network -> Cookies - the cookie comes
  
• In Application -> Cookies - empty
  

Answer 1

Remove the dot to make it just site.ru
You can set a cookie from a subdomain on a domain, but you cannot set a cookie from a domain on a subdomain - the browser will reject such a cookie.