How to forward the real client ip from Nginx Proxy Manager to a IIS server

[flowerpower]

Hi to all,
I have tried a lot of configs in "Custom locations" (you can find a screenshot in the attached images).
But the Windows IIS server in the log file of my website view only the nginx reverse proxy ip and not the client real ip.
I don't understand if I need to customize the docker config (environments variables for example) or I need to change the "proxy_set_header" declarations.
Can anyone help me?