diff --git a/config/config.inc.php.dist b/config/config.inc.php.dist
index bb047ca..cfa8f0d 100644
--- a/config/config.inc.php.dist
+++ b/config/config.inc.php.dist
@@ -1,138 +1,141 @@
 <?php
 
 // This file contains Chwala configuration options.
 // Real config file must contain or include Roundcube Framework config.
 
 // ------------------------------------------------
 // Global settings
 // ------------------------------------------------
 
 // Main files source, backend driver which handles
 // authentication and configuration of Chwala
 // Note: Currently only 'kolab' is supported
 $config['fileapi_backend'] = 'kolab';
 
 // Enabled external storage drivers
 // Note: Currenty only 'seafile' and webdav is available
 $config['fileapi_drivers'] = array('seafile', 'webdav');
 
 // Pre-defined list of external storage sources.
 // Here admins can define sources which will be "mounted" into users folder tree
 /*
 $config['fileapi_sources'] = array(
     'Seafile' => array(
         'driver' => 'seafile',
         'host'   => 'seacloud.cc',
         // when username is set to '%u' current user name and password
         // will be used to authenticate to this storage source
         'username' => '%u',
     ),
     'Public-Files' => array(
         'driver'   => 'webdav',
         'baseuri'  => 'https://some.host.tld/Files',
         'username' => 'admin',
         'password' => 'pass',
     ),
 );
 */
 
 // Default values for sources configuration dialog.
 // Note: use driver names as the array keys.
 // Note: %u variable will be resolved to the current username.
 /*
 $config['fileapi_presets'] = array(
     'seafile' => array(
         'host'     => 'seacloud.cc',
         'username' => '%u',
     ),
     'webdav' => array(
         'baseuri'  => 'https://some.host.tld/Files',
         'username' => '%u',
     ),
 );
 */
 
 // Disables listing folders from the backend storage.
 // This is useful when you configured an external source(s) and
 // you want to use it exclusively, ignoring Kolab folders.
 $config['fileapi_backend_storage_disabled'] = false;
 
 // Manticore service URL. Enables use of WebODF collaborative editor.
 // Note: this URL should be accessible from Chwala host and Roundcube host as well.
 $config['fileapi_manticore'] = null;
 
 // WOPI/Office service URL. Enables use of collaborative editor supporting WOPI.
 // Note: this URL must be accessible from the Chwala host.
 $config['fileapi_wopi_office'] = null;
 
 // Name of the user interface skin.
 $config['file_api_skin'] = 'default';
 
 // Chwala UI communicates with Chwala API via HTTP protocol
 // The URL here is a location of Chwala API service. By default
 // the UI location is used with addition of /api/ suffix.
 $config['file_api_url'] = '';
 
+// Optional server variant of file_api_url if the wopi service needs to connect via an internal url back to chwala.
+$config['file_api_server_url'] = null;
+
 // Type of Chwala cache. Supported values: 'db', 'apc' and 'memcache'.
 // Note: This is only for some additional data like WOPI capabilities.
 $config['fileapi_cache'] = 'db';
 
 // lifetime of Chwala cache
 // possible units: s, m, h, d, w
 $config['fileapi_cache_ttl'] = '1d';
 
 // LDAP addressbook that would be searched for user names autocomplete.
 // That should be an array refering to the Roundcube's $config['ldap_public']
 // array key or complete addressbook configuration array.
 $config['fileapi_users_source'] = 'kolab_addressbook';
 
 // The LDAP attribute which will be used as ACL user identifier
 $config['fileapi_users_field'] = 'mail';
 
 // The LDAP search filter will be combined with search queries
 $config['fileapi_users_filter'] = '';
 
 // Include groups in searching
 $config['fileapi_groups'] = false;
 
 // Prefix added to the group name to build IMAP ACL identifier
 $config['fileapi_group_prefix'] = 'group:';
 
 // The LDAP attribute (or field name) which will be used as ACL group identifier
 $config['fileapi_group_field'] = 'name';
 
 // ------------------------------------------------
 // SeaFile driver settings
 // ------------------------------------------------
 
 // Enables SeaFile Web API conversation log
 $config['fileapi_seafile_debug'] = false;
 
 // Enables caching of some SeaFile information e.g. folders list
 // Note: 'db', 'apc' and 'memcache' are supported
 $config['fileapi_seafile_cache'] = 'db';
 
 // Expiration time of SeaFile cache entries
 $config['fileapi_seafile_cache_ttl'] = '7d';
 
 // Default SeaFile Web API host
 // Note: http:// and https:// (default) prefixes can be used here
 $config['fileapi_seafile_host'] = 'localhost';
 
 // Enables SSL certificates validation when connecting
 // with any SeaFile server
 $config['fileapi_seafile_ssl_verify_host'] = false;
 $config['fileapi_seafile_ssl_verify_peer'] = false;
 
 // To support various Seafile configurations when fetching a file
 // from Seafile server we proxy it via Chwala server.
 // Enable this option to allow direct downloading of files
 // from Seafile server to user browser.
 $config['fileapi_seafile_allow_redirects'] = false;
 
 // ------------------------------------------------
 // WebDAV driver settings
 // ------------------------------------------------
 
 // Default URI location for WebDAV storage
 $config['fileapi_webdav_baseuri'] = 'https://localhost/iRony';