It's a DNS issue.
NEW POSTS takes me to http so not sure of your reasoning, @Joao.
The redirect was happening to me because Chrome prefers HTTPS (and also Google SEO), and because I had the New Posts link bookmarked with HTTPS, even when going to HTTP it was changing to HTTPS. Removed the bookmark and all Chrome browsing history and is not redirecting anymore.
Your HTTPS is still not well configured. Try going to https://www.print3dforum.com/ and accept to proceed. Your server is redirecting to https://cube3.print3dforum.com/
Yep indeed somethings weird in here...
Your forum because it is not working with HTTPS is being lowering the rankings on Google search. Someday they will completely remove HTTP only websites from their results, so be aware of that.
https://www.google.co.uk/webhp#q=print+3d+forum
Used to be on nr 1 now on nr 3