I am trying to append "DEV SRV:" to the page title (i.e. title tag) if the IP Address matches that of the dev server. I have tried this both in the functions.php file of my child theme and as a standalone plugin

add_filter('wp_title', 'dev_srv_title');
function dev_srv_title($title) {
        $host = $_SERVER['SERVER_ADDR'];
        if ($host =='') {
                return 'DEV SRV: '.$title;
    return $title;
  • 1
    Can you debug if $_SERVER['SERVER_ADDR'] actually has the correct value (so your if gets triggered) or if the hook is not called at all? How is the title rendered in the theme? Are you using a SEO plugin?
    – kero
    Jan 26, 2021 at 15:45
  • @kero I was able to confirm that $host has the correct value by dropping this into my child theme's header.php file: <?php $host = $_SERVER['SERVER_ADDR']; echo '<!--DEBUG SERVER ADDRESS: '.$host.'-->'; ?> I am in fact using Yoast ... that's a great question and could be the issue ... Jan 26, 2021 at 15:54
  • 1
    Quick search found these: wordpress.stackexchange.com/questions/305353/… & wordpress.stackexchange.com/questions/61472/… - does it help/answer your question?
    – kero
    Jan 26, 2021 at 16:03

1 Answer 1


The issue was not persistent between multiple installations because there were multiple themes in use. The themes were creating the title tag in different ways.

Changed plugin based solution to inserting conditional banner content (and later a contextual feedback form) in wp_footer which is working regardless of theme (so far 😉)

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