Most time it linked either to misconfigured .htaccess or the defective plugin. The solution is based on trial and error method. First, do backup/copy of .htaccess file located to the folder where WordPress site installed. In most case, it's Public_html. If you are not sure about the accuracy of code in .htaccess then temporarily replace it with WordPress's native .htaccess script (see below code).
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPressNow try to access the site. If it still keeps diverting toward 127.0.0.1 page then you need to follow the next step.
Navigate to cPanel or FTP browser and open plugin folder. Normally, located to public_html/wp-content/plugins. Now find out folders belong to security plugins. Like All in One security, WordFence, etc. Rename the folder one by one with any different name as part of a trial and error method. Remember, in most case, renaming merely All in One Security folder solves the problem. As historically this error linked to All in One WordPress Security Plugin.
Hope it will help to solve your problem. Once the website started functioning correctly then you can clean the plugin folder. If you believe the plugin is still held importance and want to reinstall then backup everything (folder+database) after that you can install that plugin again.
