diff --git a/docs/manual/warnings.md b/docs/manual/warnings.md
index baadd8f6f..75ee49174 100644
--- a/docs/manual/warnings.md
+++ b/docs/manual/warnings.md
@@ -41,6 +41,12 @@ You should be careful when changing images, environment variables, commands, or
 
 Other than the above, you can make any modifications to the pod definition you need to suit your requirements.
 
+## Limitations on FDB Port Customization
+
+The operator doesn't support to use custom ports for FDB.
+Per default a FDB cluster without TLS will use the ports `4501` and a FDB cluster using TLS will be using `4500`.
+If more than one process should be running per Pod, e.g. when using the `storagerServersPerPod` setting, the additional processes will get the `standard port + 2*processNumber`, e.g. for the second process in a TLS cluster that would be `4502`.
+
 ## Next
 
 You can continue on to the [next section](resources.md) or go back to the [table of contents](index.md).