If you have WordPress installed on your Synology, surely you have wondered which of the php extensions you need to activate for it to work. Below is a short guide that explains what you need to activate. First of all, open the application called Web Station. Once opened, go to PHP settings and then EDIT. Follow the images: (The images below work for PHP 7.2 too, even though they are about PHP 7.0)
Once you click on Edit, the following screen will open:
PHP Settings: Set PHP version to 7.2. Leave PHP Cache enabled. Select only these extensions to make WordPress work smoothly:
Press the OK button.
Note: “mcrypt” PHP extension is no longer needed when using WordPress.