--- a/plugins/mod_s2s.lua	Tue Dec 15 13:37:05 2020 +0000
+++ b/plugins/mod_s2s.lua	Wed Dec 16 08:53:57 2020 +0100
@@ -179,7 +179,7 @@
 local function keepalive(event)
 	local session = event.session;
 	if not session.notopen then
-		return event.session.send(' ');
+		return event.session.sends2s(' ');
 	end
 end