How can I access to payara 5 administration on port 4848 on a fresh installation where the FQDN is used by Payara and a mail server?

How can I access to payara administration on port 4848 on a fresh installation where the FQDN is used by Payara and a mail server?

I am trying to set a full new platform with Payara, I can’t manage to access to the administration console on port 4848.

Environment:
• OS: Debian GNU/Linux 11 (bullseye)
• Java: openjdk version “11.0.16” 2022-07-19
• Payara: Payara Server 5.2022.2 #badassfish (build 306)
• Ngnix: nginx/1.18.0

On a fresh Debian installation I first set ufw to be able to open necessary port. Then I started to install IredMail (1.6.0 MARIADB edition.). Once mail serveur was working I installed openjdk 11, then Payara. In Payara I created a domain with adminport set to 4848 and instance port set to 8888. change-admin-password and enable-secure-admin has been run for this domain.
Taking in count that my FQDN is my.domain.com, I managed to have the Payara welcome page on https: // my.domain.com, IredMail administration on https: // my.domain.com/ireadmin and IredWebMail on https: // my.domain.com/mail.
While trying to access the administation console https: // my.domain.com:4848 goes on error:
This site can’t be reached - ERR_CONNECTION_TIMED_OUT
After long search for a solution on the net, I created a dedicated url /gfadmin, see configuration below, where the page seems to be reached but I got a white page displayed. The console log shows:

gfadmin:18 GET … /theme/com/sun/webui/jsf/suntheme/css/safari.css net::ERR_ABORTED 404
gfadmin:28 GET … /theme/META-INF/prototype/prototype.js net::ERR_ABORTED 404
gfadmin:27 GET … /theme/META-INF/json/json.js net::ERR_ABORTED 404
gfadmin:29 GET … /theme/META-INF/com_sun_faces_ajax.js net::ERR_ABORTED 404
gfadmin:26 GET … /theme/META-INF/dojo/dojo.js net::ERR_ABORTED 404
gfadmin:17 GET … /theme/com/sun/webui/jsf/suntheme/css/css_master.css net::ERR_ABORTED 404
gfadmin:31 Uncaught ReferenceError: dojo is not defined
at gfadmin:31:1
(anonymous) @ gfadmin:31
gfadmin:34 GET … /resource/css/css_ns6up.css net::ERR_ABORTED 404
gfadmin:46 GET … /resource/community-theme/images/login-product_name_open.png 404
gfadmin:89 GET … /resource/js/cj.js net::ERR_ABORTED 404

as well as the nginx log shows:
0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36"
94.43.88.148 - - [12/Aug/2022:10:05:26 +0000] “GET / HTTP/2.0” 304 0 “-” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:05:29 +0000] “GET /gfadmin HTTP/2.0” 200 1705 “-” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:05:59 +0000] “GET /theme/com/sun/webui/jsf/suntheme/css/safari.css HTTP/2.0” 404 548 “… my.server.com/” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:05:59 +0000] “GET /theme/META-INF/prototype/prototype.js HTTP/2.0” 404 548 “… my.server.com/” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:05:59 +0000] “GET /theme/META-INF/json/json.js HTTP/2.0” 404 548 “… my.server.com/” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:05:59 +0000] “GET /theme/META-INF/com_sun_faces_ajax.js HTTP/2.0” 404 548 “… my.server.com/” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:05:59 +0000] “GET /theme/META-INF/dojo/dojo.js HTTP/2.0” 404 548 “… my.server.com/” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:05:59 +0000] “GET /theme/com/sun/webui/jsf/suntheme/css/css_master.css HTTP/2.0” 404 548 “… my.server.com/” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:05:59 +0000] “GET /resource/css/css_ns6up.css HTTP/2.0” 404 548 “… my.server.com/” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:06:30 +0000] “GET /resource/community-theme/images/login-product_name_open.png HTTP/2.0” 404 548 “… my.server.com/” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”
94.43.88.148 - - [12/Aug/2022:10:06:30 +0000] “GET /resource/js/cj.js HTTP/2.0” 404 548 “… my.server.com/” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”

Thinking that the issue could come from the added url /gfadmin, I set, in location {…} root to /opt/payara5/ with not result.

From /etc/ngnix/sites-vailable I remove 00-default-ssl.conf and created a new file my.server.com.conf with he following content:
upstream glassfish {
server 127.0.0.1:8888;
}
upstream gfadmin {
server 127.0.0.1:4848;
}
server {
listen 443 ssl http2;
listen [::]:443 ssl http2;
server_name my.server.com;
gzip on;
gzip_types text/css text/javascript text/plain application/xml;
gzip_min_length 1000;
location ^~ /.well-known/acme-challenge/ {
allow all;
root /var/www/my.server.com/;
default_type “text/plain”;
try_files $uri =404;
}
location / {
proxy_pass http: // localhost:8888;
proxy_connect_timeout 300;
proxy_send_timeout 300;
proxy_read_timeout 300;
send_timeout 300;
}
location ~* .(png|ico|gif|jpg|jpeg|css|js)$ {
#proxy_pass https: // localhost:8888/$request_uri;
proxy_pass https: // localhost:8888;
}
location /gfadmin {
root /opt/payara5/;
charset utf-8;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_max_temp_file_size 0;
client_max_body_size 10m;
client_body_buffer_size 128k;
proxy_send_timeout 90;
proxy_read_timeout 90;
proxy_buffering off;
proxy_buffer_size 4k;
proxy_buffers 4 32k;
proxy_busy_buffers_size 64k;
proxy_temp_file_write_size 64k;
proxy_pass https://127.0.0.1:4848;
proxy_connect_timeout 300;
send_timeout 300;
}
location /mail {
root /var/www/html;
index index.php index.html;
}
location /iredadmin {
root /var/www/html;
index index.php index.html;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
#root /usr/share/nginx/html;
root /usr/share/nginx/base;
}
#listen 80;
#listen 4848;
ssl_certificate /etc/letsencrypt/live/my.server.com/fullchain.pem; # managed by Certbot
ssl_certificate_key /etc/letsencrypt/live/my.server.com/privkey.pem; # managed by Certbot
include /etc/nginx/templates/misc.tmpl;
include /etc/nginx/templates/ssl.tmpl;
include /etc/nginx/templates/iredadmin.tmpl;
include /etc/nginx/templates/roundcube.tmpl;
include /etc/nginx/templates/sogo.tmpl;
include /etc/nginx/templates/netdata.tmpl;
include /etc/nginx/templates/php-catchall.tmpl;
include /etc/nginx/templates/stub_status.tmpl;
}

I would appreciate any help that will allow me to fix this issue.
Thank you