diff -r 4c91afc43639 -r 7fa273f8869e plugins/mod_s2s/mod_s2s.lua
--- a/plugins/mod_s2s/mod_s2s.lua	Mon Jan 14 00:17:02 2019 +0100
+++ b/plugins/mod_s2s/mod_s2s.lua	Tue Jan 15 20:08:30 2019 +0100
@@ -595,8 +595,7 @@
 		if data then
 			local ok, err = stream:feed(data);
 			if ok then return; end
-			log("warn", "Received invalid XML: %s", data);
-			log("warn", "Problem was: %s", err);
+			log("debug", "Received invalid XML (%s) %d bytes: %q", tostring(err), #data, data:sub(1, 300));
 			session:close("not-well-formed");
 		end
 	end