HTTPS connection to API not working Express/Node/Nginx

I have a AWS instance running and created a certificate using certbot: I can go with the browser to https://www.tichutimo.ch/ and it shows the default page. There is a route configured http://www.tichutimo.ch:5000/api/users/test which just responds with some text. With http this works fine. But when I try https://www.tichutimo.ch:5000/api/users/test I get "SSL_ERROR_RX_RECORD_TOO_LONG" in firefox.

Now I am not even sure where to look for a solution: In express? In nginx? I don't see anything in my express logs..

With curl i get curl: (35) error:1400410B:SSL routines:CONNECT_CR_SRVR_HELLO:wrong version number