问SSL证书在后端节点应用程序上无效(Nginx反向代理)

EN

server {
  listen 80 ssl;
  server_name xx.xx.xxx.xx;
  ssl_client_certificate /etc/letsencrypt/live/domain.com/cert.pem;
  ssl_certificate /etc/letsencrypt/live/domain.com/cert.pem;
  ssl_certificate_key /etc/letsencrypt/live/domain.com/privkey.pem;
  root /home/ubuntu/build;
  index index.html;

  access_log /var/log/nginx/build.access.log;
  error_log /var/log/nginx/build.error.log;
  location / {
    try_files $uri /index.html =404;
  }
}

upstream backend {
  server 127.0.0.1:443;
  server 127.0.0.1:443 max_fails=1 fail_timeout=30s backup;
  keepalive 64;
}

server {
  listen 443 ssl;
  server_name xx.xx.xxx.xx;
  ssl_client_certificate /etc/letsencrypt/live/domain.com/cert.pem;
  ssl_certificate /etc/letsencrypt/live/domain.com/cert.pem;
  ssl_certificate_key /etc/letsencrypt/live/domain.com/privkey.pem;
  keepalive_timeout 10;
  location / {
    proxy_pass http://backend;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_next_upstream error timeout http_500 http_502 http_503 http_504;
    proxy_set_header Connection '';
    proxy_set_header Host $host;
    proxy_cache_bypass $http_upgrade;
    proxy_redirect off;
   }
}