we created a page and set the template to Portfolio Page. There we selected categories of portfolio items that should connect with the page. It seems though that these categories are automatically ordered alphabetically. We want them to appear in a particular order. How can we manage that?
No, this is a free plugin. You can install it directly from your WordPress > Plugins > Add New, menu. Or download it here: https://wordpress.org/plugins/post-types-order/ and import the zip file like any other plugin.
