Thanks again!
If I am doing "mobile friendly test" for the page Google doesn't seem to have any problems accessing the mobile version. If also crawled the page with googles mobile crawler in screamingfrog and again there were not issues.
So I don't think the rather unusual behavior of not beeing able to access the mobile site with a desktop browser has an impact on my question regarding the desktop "rich snippets for ratings" showing up in mobile search results.