The easiest way to test these kinds of things is to use curl. I made a request in the Mac terminal for your site like this:
$ curl -I https://www.servermeister.nl curl: (35) Unknown SSL protocol error in connection to www.servermeister.com:-9838
The “-I” flag means to just show the header response. This tells me it couldn’t even establish an SSL connection to the server. Since I knew the domain was pointing to CloudFlare, that gave me enough info to assume that the problem was at CloudFlare.
When you make a request you can also check the app’s Nginx access log to see if it even gets to the server. In this case I didn’t see any requests reaching your server, so felt strongly that it wasn’t getting past CloudFlare.