A while ago I posted a guide how to set up nginx as a reverse proxy in front of tomcat to run ORDS and APEX. See the post here.
An open problem was that APEX was still thinking it runs on port 80 with http, while nginx was running https on port 443.
The fix to this is editing tomcats server.xml file and adding proxyPort and scheme (documentation) to the connector:
Restart tomcat and everything looks fine !
Why is that even important? Everything seems to work fine, anyways.
In some situations APEX internally creates a redirect to a different URL path, e.g. during Authentication using Social-Login it will redirect to …/ords/apex_authentication.callback… . At this redirect APEX constracts the full URL using protocol and port information from above displayed CGI variables and would hence redirect to http and port 80 instead of https.