title: Password protected page not redirecting correctly when password is supplied
body: <p>Inherited a site with a convoluted setup.</p>
  
  <p>wp-login.php is served by a different subdomain than the page being password protected. It is also behind https while the password protected page is not.</p>
  
  <p>When the correct password is supplied the form action goes to <a href="https://backend.sitename.com/wp-login.php?action=postpass" rel="nofollow noreferrer">https://backend.sitename.com/wp-login.php?action=postpass</a> and is redirected back to <a href="http://frontend.sitename.com/pagename/" rel="nofollow noreferrer">http://frontend.sitename.com/pagename/</a> with the password form presented again.</p>
  
  <p>The developer console throws up a few warnings about cookies without a SameSite attribute set.</p>
  
  <p>Not sure on the best way to correct this?</p>