Error 403 return keycloak

Hi!,

We need help with our new infraestructure.
We have three instances, one for our app, other for Nginx and the third for keycloak.

Nginx is between the other two instances. When we want to do logging in our APP, the request pass througth nginx to keycloak and return by nginx to APP.
But we have an issue:

195.55.133.108 - - [03/Jan/2020:12:10:32 +0100] "GET /APP/?state=de9634c8-d409-418f-9b3d-78cacd36e0fe&session_state=4f425be9-1cf1-4340-b05f-0189bf86b89b&code=8ba8c7c4-3b32-43d3-b146-91265c79add1.4f425be9-1cf1-4340-b05f-0189bf86b89b.f91920a4-3267-4de5-9788-24093a32c217 HTTP/1.1" 403 418 "https://our_domain/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:71.0) Gecko/20100101 Firefox/71.0"

Could you help us, please?

We have read the keycloak documentation and the parameters are:

proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-Port $server_port;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;