How to configure nginx+xbt?

Question

Nginx

There is a VPS - a gateway for the main server, all sites go through the gateway, but xbt cannot connect to the main server, how to set it up ?? I tried through nginx but I don't know what to do with passkey?
nginx config in gateway

server {
server_name site.ru www.site.ru;
listen ip_gateway;
location / {
proxy_pass http://ip_main_server:81;
proxy_redirect http://ip_main_server:81/ /;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Real-IP $remote_addr;
}
location ~ ^/[0-9a-fA-F]\/(an|announce) {
proxy_pass http://ip_main_server:2710;
proxy_redirect off;
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $remote_addr;
}
include /usr/local/ispmgr/etc/nginx.inc;
}

there was an idea to forward ports through the ip table, but I don’t know how it’s done ...