diff --git a/doc/uhub.conf b/doc/uhub.conf
index 428b515..12017a9 100644
--- a/doc/uhub.conf
+++ b/doc/uhub.conf
@@ -86,6 +86,11 @@ chat_is_privileged = no
 # non-operator users.
 chat_only = no
 
+# if obsolete_clients=1 allows old clients to enter , 0 gives an error message (msg_proto_obsolete_adc0) if they try connect
+# defaults obsolete_clients=1
+obsolete_clients=1
+
+
 # Configure status message as sent to clients in different circumstances.
 msg_hub_full                   = Hub is full
 msg_hub_disabled               = Hub is disabled