I have read the tutorial on how to make nginx a transparent proxy but my needs are a bit different and I don't have all the skills I need to accomplish the goal. I already have apache 2.4 named virtual host serving 2 domains. I also have ssl certificates thru let's encrypt with cron to renew prior to the 90 expiration. My router is already forwarding on 80 and 443 for secure connections. The router won't allow more than 1 forward and I want to setup ubuntu server 16.04 to run email with rouncube along with postfix/dovecot. I already know extra steps are needed to pass the header so the secure connection will work on port 443. I found one tutorial but it only worked on localhost as going to the domain brought up the default nginx page. So it wasn't passing the internal ip from outside. Can anyone point me to a tutorial on how to do this? Also I'm running the web server on virtual machine in VMware workstation.
I will be happy to draw up a topology for you to look at. I will post it a little later today my time. Ports 80 and 443 again as I already have my router forwarding already those common ports.