Usando print_r($_SERVER) ricevo questa risposta:

Array
(
[USER] => admin_enigma
[HOME] => /var/www/vhosts/enigma3.it
[SCRIPT_NAME] => /index.php
[REQUEST_URI] => /
[QUERY_STRING] =>
[REQUEST_METHOD] => GET
[SERVER_PROTOCOL] => HTTP/1.0
[GATEWAY_INTERFACE] => CGI/1.1
[REMOTE_PORT] => 39350
[SCRIPT_FILENAME] => /var/www/vhosts/enigma3.it/httpdocs/test-sviluppo/index.php
[SERVER_ADMIN] => root@localhost
[CONTEXT_DOCUMENT_ROOT] => /var/www/vhosts/enigma3.it/httpdocs/test-sviluppo
[CONTEXT_PREFIX] =>
[REQUEST_SCHEME] => https
[DOCUMENT_ROOT] => /var/www/vhosts/enigma3.it/httpdocs/test-sviluppo
[REMOTE_ADDR] => 81.208.11.32
[SERVER_PORT] => 443
[SERVER_ADDR] => 195.231.22.14
[SERVER_NAME] => sviluppo.enigma3.it
[SERVER_SOFTWARE] => Apache
[SERVER_SIGNATURE] =>
[PATH] => /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
[HTTP_COOKIE] => PHPSESSID=b774aelnkusu0c8thd0abgjmv8
[HTTP_SEC_GPC] => 1
[HTTP_SEC_FETCH_USER] => ?1
[HTTP_SEC_FETCH_SITE] => none
[HTTP_SEC_FETCH_MODE] => navigate
[HTTP_SEC_FETCH_DEST] => document
[HTTP_UPGRADE_INSECURE_REQUESTS] => 1
[HTTP_ACCEPT_ENCODING] => gzip, deflate, br
[HTTP_ACCEPT] => text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
[HTTP_USER_AGENT] => Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:106.0) Gecko/20100101 Firefox/106.0
[HTTP_CONNECTION] => close
[HTTP_X_ACCEL_INTERNAL] => /internal-nginx-static-location
[HTTP_X_REAL_IP] => 81.208.11.32
[HTTP_HOST] => sviluppo.enigma3.it
[proxy-nokeepalive] => 1
[HTTPS] => on
[PERL5LIB] => /usr/share/awstats/lib:/usr/share/awstats/plugins
[UNIQUE_ID] => Y1JY1Fhdr0V7DF1iQCnE@wAAAAQ
[FCGI_ROLE] => RESPONDER
[PHP_SELF] => /index.php
[REQUEST_TIME_FLOAT] => 1666341076.8809
[REQUEST_TIME] => 1666341076
)

Nessun riferimento alla lingua del browser.