diff --git a/rpm/sources/qgis-server-README.fedora b/rpm/sources/qgis-server-README.fedora
index c2f4ff8760b..0c7c34dd9b7 100644
--- a/rpm/sources/qgis-server-README.fedora
+++ b/rpm/sources/qgis-server-README.fedora
@@ -25,8 +25,10 @@ QGIS project is "/var/www/ows/my_qgis_project.qgs". The sample
 configuration automatically adds the project file extension for you.
 
 The actual data can stay where it is. Make sure QGIS server can
-access the project file and don't forget to let Httpd reload its
-configuration before sending your requests!
+access the project file and don't forget to let the web server reload its
+configuration before sending your requests! Make also sure that
+the environment variable 'QGIS_PREFIX_PATH' is set to '/usr' before
+running the FCGI server; see the examples for further details.
 
 Please fill in the metadata tab for your QGIS project.
 
diff --git a/rpm/sources/qgis-server-fcgi.service b/rpm/sources/qgis-server-fcgi.service
index 09138b3976f..2d3addcc41e 100644
--- a/rpm/sources/qgis-server-fcgi.service
+++ b/rpm/sources/qgis-server-fcgi.service
@@ -10,6 +10,10 @@ After = network.target qgis-server-fcgi.socket
 # An existing user must be set
 User = qgis
 Group = qgis
+Environment = "QGIS_PREFIX_PATH=/usr" "QGIS_SERVER_LOG_STDERR=true"
+# See https://docs.qgis.org//en/docs/user_manual/working_with_ogc/server/config.html
+# for the full list of supported environment variables, i.e.:
+# Environment = "QGIS_SERVER_PARALLEL_RENDERING=true"
 ExecStart = /usr/libexec/qgis/qgis_mapserv.fcgi
 StandardInput = socket
 WorkingDirectory = /tmp
diff --git a/rpm/sources/qgis-server-httpd.conf b/rpm/sources/qgis-server-httpd.conf
index 29609322ebc..ab0b461fd2b 100644
--- a/rpm/sources/qgis-server-httpd.conf
+++ b/rpm/sources/qgis-server-httpd.conf
@@ -10,6 +10,10 @@ ScriptAlias /qgis/ "/usr/libexec/qgis/"
 
   Options ExecCGI
   Options FollowSymLinks
+  FcgidInitialEnv QGIS_PREFIX_PATH=/usr
+  # See https://docs.qgis.org//en/docs/user_manual/working_with_ogc/server/config.html
+  # for the full list of supported environment variables, i.e.:
+  # FcgidInitialEnv QGIS_SERVER_PARALLEL_RENDERING=true
 
   <IfModule mod_authz_core.c>
     # Apache 2.4
diff --git a/rpm/sources/qgis-server-nginx.conf b/rpm/sources/qgis-server-nginx.conf
index bd377fdc926..64cc2d7f99c 100644
--- a/rpm/sources/qgis-server-nginx.conf
+++ b/rpm/sources/qgis-server-nginx.conf
@@ -22,24 +22,26 @@ http {
     include             /etc/nginx/mime.types;
     default_type        application/octet-stream;
 
-    # Get 'port' from `$http_host`
+    # Get 'host' from `$host` unless 'X-Forwarded-Host'
+    # is set by the reverse proxy.
+    # 'X-Forwarded-Host' may contain also the port,
+    # so it is removed from the variable
+    map $http_x_forwarded_host $qgis_host {
+        "~(?<h>[^:]+)" $h;
+        default $host;
+    }
+    # Get 'PORT' from `$http_host`
     map $http_host $port {
         "~*.*:(?<p>.*)" $p;
-        default server_port;
+        default $server_port;
     }
-    # Get 'proto' from `$scheme` unless 'X-Forwarded-Proto'
-    # is set by the reverse proxy
-    map $http_x_forwarded_proto $qgis_proto {
-        "" $scheme;
-        default $http_x_forwarded_proto;
+    # Get 'HTTPS' status from `$https` unless 'X-Forwarded-Proto'
+    # is set by the reverse proxy and contains 'https' scheme
+    map $http_x_forwarded_proto $qgis_ssl {
+        "https" "on";
+        default $https;
     }
-    # Get 'host' from `$host` unless 'X-Forwarded-Host'
-    # is set by the reverse proxy
-    map $http_x_forwarded_host $qgis_host {
-        "" $host;
-        default $http_x_forwarded_host;
-    }
-    # Get 'port' from `$port` unless 'X-Forwarded-Port'
+    # Get 'PORT' from `$port` unless 'X-Forwarded-Port'
     # is set by the reverse proxy
     map $http_x_forwarded_port $qgis_port {
         "" $port;
@@ -63,9 +65,10 @@ http {
             fastcgi_param QUERY_STRING    $query_string;
             # build links in GetCapabilities based on
             # the hostname exposed by the reverse proxy
-            fastcgi_param  SERVER_PROTOCOL $qgis_proto;
+            fastcgi_param  HTTPS $qgis_ssl;
             fastcgi_param  SERVER_NAME $qgis_host;
             fastcgi_param  SERVER_PORT $qgis_port;
+            include fastcgi_params;
         }
         error_page 404 /404.html;
             location = /40x.html {