How to implement below config on nginx Reverse Proxy mode

[blason]

Hi Team,

My nginx is configured in Reverse Proxy mode and catering to internet. 
However I have been tasked to add one e server with below config and I am
facing difficulty while putting that in production.

My scenario is I have internal server which accessed then gets diverted on
to other port and long URL

Internal IP address/URL  is and mapped to external URL as
https://xyz.example.com
https://xyz.example.com
Once this URL accessed it get turned into
https://xyz.example.com:8443/PortalLgin/action.do?portal=a8550fd2-24bb-11e6-a111

I have tried configuring Proxy_pass as 
https://xyz.example.com:8443/PortalLgin/action.do?portal=a8550fd2-24bb-11e6-a111

But no luck
Tried listen Directive 8443 still no luck
Can someone please suggest?

Thanks and Regards,
Blason R

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,282809,282809#msg-282809