Issues with 502 Gateway

Hi,
I’m using pfsense and Haproxy built in ( v 2.7.8-58c657f ) . I use haproxy as SSL offloading and redirecting to different servers behind in http the different sites.
Checked some post and I look to be aligned with good practices and samples I found.
I’m having issues browsing a Joomla website ( name in conf is “stream” ) and can not find the issue. 502 seems to appear when a form submission is done.

Here is the config automatically generated below

# Automaticaly generated, dont edit manually.
# Generated on: 2024-05-03 09:36
global
        maxconn                 5000
        log                     /var/run/log    syslog  debug
        stats socket /tmp/haproxy.socket level admin  expose-fd listeners
        uid                     80
        gid                     80
        nbthread                        1
        hard-stop-after         15m
        chroot                          /tmp/haproxy_chroot
        daemon
        tune.ssl.default-dh-param       2048
        log-send-hostname               MAIN
        server-state-file /tmp/haproxy_server_state

listen HAProxyLocalStats
        bind 127.0.0.1:2200 name localstats
        mode http
        stats enable
        stats refresh 10
        stats admin if TRUE
        stats show-legends
        stats uri /haproxy/haproxy_stats.php?haproxystats=1
        timeout client 5000
        timeout connect 5000
        timeout server 5000

frontend Main_FrontEnd
        bind                    MY_PUBLIC_IP:443 name MY_PUBLIC_IP:443   ssl crt-list /var/etc/haproxy/Main_FrontEnd.crt_list
        mode                    http
        log                     global
        option                  httplog
        option                  http-keep-alive
        option                  forwardfor
        acl https ssl_fc
        http-request set-header         X-Forwarded-Proto http if !https
        http-request set-header         X-Forwarded-Proto https if https
        timeout client          30000
        acl                     Direct  var(txn.txnhost) -m str -i cleafy.MY_DOMAIN.com
        acl                     Stream  var(txn.txnhost) -m str -i cleafystream.MY_DOMAIN.com
        acl                     Wordpress       var(txn.txnhost) -m str -i wordpress.MY_DOMAIN.com
        acl                     MoodleSSL       var(txn.txnhost) -m str -i moodle.MY_DOMAIN.com
        acl                     aclcrt_Main_FrontEnd    var(txn.txnhost) -m reg -i ^([^\.]*)\.MY_DOMAIN\.com(:([0-9]){1,5})?$
        http-request set-var(txn.txnhost) hdr(host)
        use_backend Direct_ipvANY  if  Direct aclcrt_Main_FrontEnd
        use_backend Stream_ipvANY  if  Stream aclcrt_Main_FrontEnd
        use_backend Wordpress_ipvANY  if  Wordpress aclcrt_Main_FrontEnd
        use_backend Moodle-SSL_ipvANY  if  MoodleSSL aclcrt_Main_FrontEnd


backend Direct_ipvANY
        mode                    http
        id                      110
        log                     global
        timeout connect         30000
        timeout server          30000
        retries                 3
        load-server-state-from-file     global
        server                  Moodle-SSL X.Y.Z.114:80 id 101 check inter 1000

backend Stream_ipvANY
        mode                    http
        id                      111
        log                     global
        timeout connect         30000
        timeout server          30000
        retries                 3
        load-server-state-from-file     global
        server                  Moodle-SSL X.Y.Z.175:80 id 101 check inter 1000

backend Wordpress_ipvANY
        mode                    http
        id                      112
        log                     global
        timeout connect         30000
        timeout server          30000
        retries                 3
        load-server-state-from-file     global
        server                  Moodle-SSL X.Y.Z.119:80 id 101 check inter 1000

backend Moodle-SSL_ipvANY
        mode                    http
        id                      100
        log                     global
        timeout connect         30000
        timeout server          30000
        retries                 3
        load-server-state-from-file     global
        server                  Moodle-SSL X.Y.Z.145:80 id 101 check inter 1000

I don’t think I’m doign someting exotic, so any option that I would be missing ?
Thanks for your insights