DNS 504 Gateway Time-out

Hello,

I’m new using Mailcow and not too good with coding.
I’m using an Opnsense as firewall with HA proxy and Mailcow in a Ubuntu server 24.04 only for Mailcow.
I noted Mailcow as by default fail2ban, because it is behind a proxy, I had to adjust the settings to make it to read the proxy setting and then read the real IP for incoming connections.
I think after that the domain check stopped working, I had enabled in Opnsense DNS override for the domains in Mailcow, I changed the DNS for the server to 1.1.1..1, disabled the DNS override in Opnsense.
The DNS is working fine but the DNS record check for the domains still falling.
I rebooted the server, cleared the cache, and restarted the docker and still having the issue.
After reading in the community I realized could be the setting I made for HAproxy.
Can you help me to understand what setting must be adjusted to make it work?

My nginx config, I think is it:
root@mailcow:/home/uroot# cat /opt/mailcow-dockerized/data/conf/nginx/templates/nginx.conf.j2
user nginx;
worker_processes auto;

error_log /var/log/nginx/error.log notice;
pid /var/run/nginx.pid;

events {
worker_connections 1024;
}

http {
include /etc/nginx/mime.types;
default_type application/octet-stream;

log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for"';

access_log  /var/log/nginx/access.log  main;

sendfile        on;
#tcp_nopush     on;

keepalive_timeout  65;

#gzip  on;

# map-size.conf:
map_hash_max_size 256;
map_hash_bucket_size 256;

# site.conf:
proxy_cache_path /tmp levels=1:2 keys_zone=sogo:10m inactive=24h  max_size=1g;
server_names_hash_max_size 512;
server_names_hash_bucket_size 128;

map $http_x_forwarded_proto $client_req_scheme {
set_real_ip_from 10.17.17.254;
real_ip_header X-Forwarded-For;
real_ip_recursive on;

    default $scheme;
    https https;
}

{% if HTTP_REDIRECT %}
# HTTP to HTTPS redirect
server {
    root /web;
    listen {{ HTTP_PORT }} proxy_protocol;
    listen [::]:{{ HTTP_PORT }} proxy_protocol;

    server_name {{ mailcow }} autodiscover.* autoconfig.* {{ ADDITIONAL_SERVER_NAMES | join(' ') }};

    if ( $request_uri ~* "%0A|%0D" ) { return 403; }
    location ^~ /.well-known/acme-challenge/ {
        allow all;
        default_type "text/plain";
    }
    location / {
        return 301 https://$host$uri$is_args$args;
    }
}
{%endif%}

# Default Server Name
server {
    listen 127.0.0.1:65510; # sogo-auth verify internal

    {% if not HTTP_REDIRECT %}
    listen {{ HTTP_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%};
    {%endif%}
    listen {{ HTTPS_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%} ssl;

    {% if not DISABLE_IPv6 %}
    {% if not HTTP_REDIRECT %}
    listen [::]:{{ HTTP_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%};
    {%endif%}
    listen [::]:{{ HTTPS_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%} ssl;
    {%endif%}

    http2 on;

    ssl_certificate /etc/ssl/mail/cert.pem;
    ssl_certificate_key /etc/ssl/mail/key.pem;

    server_name {{ mailcow }} autodiscover.* autoconfig.*;

    include /etc/nginx/includes/sites-default.conf;
}

# Additional Server Names
{% for SERVER_NAME in ADDITIONAL_SERVER_NAMES %}
server {
    listen 127.0.0.1:65510; # sogo-auth verify internal

    {% if not HTTP_REDIRECT %}
    listen {{ HTTP_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%};
    {%endif%}
    listen {{ HTTPS_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%} ssl;

    {% if not DISABLE_IPv6 %}
    {% if not HTTP_REDIRECT %}
    listen [::]:{{ HTTP_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%};
    {%endif%}
    listen [::]:{{ HTTPS_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%} ssl;
    {%endif%}

    http2 on;

    ssl_certificate /etc/ssl/mail/cert.pem;
    ssl_certificate_key /etc/ssl/mail/key.pem;

    server_name {{ SERVER_NAME }};

    include /etc/nginx/includes/sites-default.conf;
}
{% endfor %}

# rspamd dynmaps:
server {
    listen 8081;
    {% if not DISABLE_IPv6 %}
    listen [::]:8081;
    {%endif%}
    index index.php index.html;
    server_name _;
    error_log  /var/log/nginx/error.log;
    access_log /var/log/nginx/access.log;
    root /dynmaps;

    location ~ \.php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass {{ PHPFPMHOST }}:9001;
        fastcgi_index index.php;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
    }
}

# rspamd meta_exporter:
server {
    listen 9081;
    index index.php index.html;
    server_name _;
    error_log  /var/log/nginx/error.log;
    access_log /var/log/nginx/access.log;
    root /meta_exporter;
    client_max_body_size 10M;
    location ~ \.php$ {
        client_max_body_size 10M;
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass {{ PHPFPMHOST }}:9001;
        fastcgi_index pipe.php;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
    }
}

{% for cert in valid_cert_dirs %}
server {
    {% if not HTTP_REDIRECT %}
    listen {{ HTTP_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%};
    {%endif%}
    listen {{ HTTPS_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%} ssl;

    {% if not DISABLE_IPv6 %}
    {% if not HTTP_REDIRECT %}
    listen [::]:{{ HTTP_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%};
    {%endif%}
    listen [::]:{{ HTTPS_PORT }}{% if NGINX_USE_PROXY_PROTOCOL %} proxy_protocol{%endif%} ssl;
    {%endif%}

    http2 on;

    ssl_certificate {{ cert.cert_path }}cert.pem;
    ssl_certificate_key {{ cert.cert_path }}key.pem;

    server_name {{ cert.domains }};

    include /etc/nginx/includes/sites-default.conf;
}
{% endfor %}

include /etc/nginx/conf.d/*.conf;

}
root@mailcow:/home/uroot#

Thanks in advance for your help and patience.

Regards!