Left-right navigation of portfolio item ignores portfolio category.

Hello,

I have a problem with my portfolio-nagivation (the one at the left and right edge of every portfolio item).

I have 3 portfolio-pages: ‘Referenties’, ‘Te koop’ and ‘Te huur’ with projects from it’s own category.
When using the navigation to go to the previous and next projects I end up switching to projects in another category. (example in private content)
I guess this navigation uses the list of ALL portfolio projects, not only the ones in that category.

Is it possible to only navigate inside one category, not all projects?

Kind regards,
Pj