If your site shows a “Site Currently Unavailable” message, don’t panic. Start...

https://alpha-wiki.win/index.php/Site_Currently_Unavailable_on_One_Browser_Only:_Causes_and_Solutions

If your site shows a “Site Currently Unavailable” message, don’t panic. Start by checking your DNS settings to ensure your domain points correctly. Next, review permission errors like 403 or authentication issues such as 401