diff --git a/matrix/synapse/README.md b/matrix/synapse/README.md
index acda812..3e06cbb 100644
--- a/matrix/synapse/README.md
+++ b/matrix/synapse/README.md
@@ -30,7 +30,15 @@ be configured with yaml-files in this directory.
 
 Configure the domain you with to use in `/etc/matrix-synapse/conf.d/server_name.yaml`.
 What you configure here will also be the global part of your Matrix handles
-(the part after the colon).
+(the part after the colon). Also add the URL clients should connect to:
+
+```
+server_name: example.com
+public_baseurl: https://matrix.example.com/
+```
+
+The `public_baseurl` will probably be different than the `server_name`, see
+also [Delegation and DNS].
 
 You now have a standard Matrix server that uses sqlite. You really don't want
 to use this in production, so probably want to replace this with PostgreSQL.