diff --git a/docs/faq.md b/docs/faq.md
index 83f350d..590c68e 100644
--- a/docs/faq.md
+++ b/docs/faq.md
@@ -7,3 +7,4 @@ Check that
 * `SCREEGO_EXTERNAL_IP` is set to your external IP. See [Configuration](config.md)
 * you are using TURN for NAT-Traversal. See [NAT-Traversal](nat-traversal.md). *This isn't allowed for app.screego.net, you've to self-host Screego*
 * your browser doesn't block WebRTC (extensions or other settings)
+* you have opened ports in your firewall. By default 5050, 3478 and any UDP port when using TURN.