Navigate through same category posts only in category page

Hi all,

I’m currently trying to setup two news pages, one public page, one private (internal) page:
– On the public page, posts from all categories but the internal one should be displayed. I did hide the internal category from the catergoryfilter with css alreay.
– The internal news page will be the catergory page of that category. Here I can hide the entire filter-bar.

The issue that occurs now is that whenever I click on a post and navigate through the prev. and next posts, also posts from the other categories are shown (on the internal page the public ones, and more importantly, the internal news on the public news page.

I found that I can navigate through the same category only, but that#s not desired for the public news page where only the internal news should be skipped.

Is this plan possible to realize (at all)?
If so, I’d very much appreciate some help as I’m not that much into PHP and WP ??

Thanks!