how to proxy through nginx server to nginx ingress controller

Question

there are two servers

1. external server on it nginx server
2. internal access to it only through an external server, and also k8s with nginx ingress controller is installed on it

the problem is that I can't get proxying from k8srancher.ru to rancher.k8smaster.ru to work if proxy_set_header Host $host; is in the external nginx config, then when you go to the site, the error 404 Not Found if you remove it, the site opens but does not work correctly (I can’t even log in)

tell me where and what to add so that proxying works correctly

External server code nginx server /etc/nginx/conf.d/rancher.conf

map $http_upgrade $connection_upgrade {
    default Upgrade;
    ''      close;
}

server {
        listen 80;
        server_name k8srancher.ru;
        return 301 https://$server_name$request_uri;
}

server {
        listen 443 ssl http2;
        server_name k8srancher.ru;
        ssl_prefer_server_ciphers on;

        ssl_session_timeout 1d;
        ssl_verify_client off;
        ssl_session_cache  builtin:1100  shared:SSL:10m;
        ssl_protocols TLSv1.2 TLSv1.3;
        ssl_ciphers EECDH:+AES256:-3DES:RSA+AES:RSA+3DES:!NULL:!RC4;


        ssl_certificate /etc/nginx/ssl/k8soshift.ru.pem;
        ssl_certificate_key /etc/nginx/ssl/k8soshift.ru.key;

        location / {
#               proxy_set_header Host $host;
                proxy_set_header X-Forwarded-Proto $scheme;
                proxy_set_header X-Forwarded-Port $server_port;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_pass http://rancher.k8smaster.ru/;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection $connection_upgrade;
        }
}

ingress controller config file on back end server (kubectl edit cm -n ingress-nginx ingress-nginx-controller)

apiVersion: v1
data:
allow-snippet-annotations: "true"
use-forwarded-headers: "true"
kind: ConfigMap
metadata:
annotations:
    meta.helm.sh/release-name: ingress-nginx
    meta.helm.sh/release-namespace: ingress-nginx
creationTimestamp: "2022-05-01T12:17:11Z"
labels:
    app.kubernetes.io/component: controller
    app.kubernetes.io/instance: ingress-nginx
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
    app.kubernetes.io/version: 1.2.0
    helm.sh/chart: ingress-nginx-4.1.0
name: ingress-nginx-controller
namespace: ingress-nginx
resourceVersion: "31126"
uid: 0db55f76-6e6d-45a8-8996-abc7478ebc28

file ingress rancher.k8smaster.ru (kubectl edit ingress rancher -n cattle-system)

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
annotations:
    cert-manager.io/issuer: rancher
    cert-manager.io/issuer-kind: Issuer
    field.cattle.io/publicEndpoints: '[{"addresses":["10.209.40.2"],"port":443,"protocol":"HTTPS","serviceName":"cattle-system:rancher","ingressName":"cattle-system:rancher","hostname":"rancher.k8smaster.ru","allNodes":false}]'
    kubernetes.io/ingress.class: nginx
    meta.helm.sh/release-name: rancher
    meta.helm.sh/release-namespace: cattle-system
    nginx.ingress.kubernetes.io/configuration-snippet: |
    more_set_headers "Host k8srancher.ru";
    more_set_headers "X-Forwarded-Proto $scheme";
    more_set_headers "X-Forwarded-Port $server_port";
    more_set_headers "X-Forwarded-For $proxy_add_x_forwarded_for";
    more_set_headers "X-Real-IP $remote_addr";
    nginx.ingress.kubernetes.io/proxy-connect-timeout: "30"
    nginx.ingress.kubernetes.io/proxy-read-timeout: "1800"
    nginx.ingress.kubernetes.io/proxy-send-timeout: "1800"
creationTimestamp: "2022-05-01T12:32:56Z"
generation: 1
labels:
    app: rancher
    app.kubernetes.io/managed-by: Helm
    chart: rancher-2.6.4
    heritage: Helm
    release: rancher
name: rancher
namespace: cattle-system
resourceVersion: "71869"
uid: 89245b12-68f9-4e7b-a074-527505b84c73
spec:
ingressClassName: nginx
rules:
- host: rancher.k8smaster.ru
    http:
    paths:
    - backend:
        service:
            name: rancher
            port:
            number: 80
        pathType: ImplementationSpecific
tls:
- hosts:
    - rancher.k8smaster.ru
    secretName: tls-rancher-ingress
status:
loadBalancer:
    ingress:
    - ip: 10.209.40.2