[Plugin: WP-PageNavi] Page 2 >> 404

I’m having a bit of an issue and since i don’t really have any knowledge on php im not sure if it’s the theme or the plugin doing this, but anyways here it goes:

https://www.mori-visuals.com/category/portfolio/

If you click on the link above, at the very bottom of the page if you click Page 2 it redirects me to a 404 page.

And I have no clue where to start looking for the error… any help or tips would be greatly appreciated. Thanks ahead of time!