diff --git a/lib/file_wopi.php b/lib/file_wopi.php
--- a/lib/file_wopi.php
+++ b/lib/file_wopi.php
@@ -97,8 +97,10 @@
             return;
         }
 
-        $office_url  = rtrim($metadata['urlsrc'], ' /?'); // collabora
-        $service_url = $this->api->api_url() . '/wopi/files/' . $id;
+        $office_url = rtrim($metadata['urlsrc'], ' /?'); // collabora
+        //Configurable if e.g. collabora does not connect via the public url
+        $service_url = $this->rc->config->get('file_api_server_url', $this->api->api_url());
+        $service_url = rtrim($service_url, ' /') . '/wopi/files/' . $id;
 
         // @TODO: Parsing and replacing placeholder values
         // https://wopi.readthedocs.io/en/latest/discovery.html#action-urls
@@ -173,8 +175,8 @@
             return $this->apply_aliases_and_exceptions($result);
         }
 
-        $office_url  = rtrim($this->rc->config->get('fileapi_wopi_office'), ' /');
-        $office_url .= '/hosting/discovery';
+        $office_url = $this->rc->config->get('fileapi_wopi_office_server', $this->rc->config->get('fileapi_wopi_office'));
+        $office_url = rtrim($office_url, ' /') . '/hosting/discovery';
 
         try {
             $request = $this->http_request();