Search for Blog posts – A standalone search box – Is it possible?

I am using DT 8.8

I have Advanced Search activated in pages and as a widget in sidebars – it works perfectly for searching listings by keyword and category – just as I want it to. So far so good.

What I would like to achieve is a separate search-box for my blog posts – just as I have a separate search-box for my forums’ content.

I have tried the WP standard widget search-box, it returns no results.

If I check the check-box to select blog posts as well as listings in the advanced search (in General Settings > Search Setup > Custom Orderby Options) I still get the listings but no blog posts.

I have tried all of the above with all plugins disabled – no change.

I tried downloading a search plugin but that broke the existing Advanced Search so was binned!

Any suggestions gratefully received.
Many thanks.