diff --git a/docs/admin-manual/custom-authentication.md b/docs/admin-manual/custom-authentication.md
index 08987613d..c9cde9fe4 100644
--- a/docs/admin-manual/custom-authentication.md
+++ b/docs/admin-manual/custom-authentication.md
@@ -3,6 +3,12 @@ title: Custom authentication
 sidebar_position: 40
 ---
 
+:::warning
+
+Since LibreTime v3.0.0-alpha.13, this documentation is out of date, as it relies on the Apache2 web server and the default web server installed by LibreTime is now NGINX.
+
+:::
+
 ## Setup FreeIPA authentication
 
 You can configure LibreTime to delegate all authentication to a FreeIPA server.