--- a/plugins/mod_s2s/mod_s2s.lua	Sun Jun 10 17:45:49 2018 +0200
+++ b/plugins/mod_s2s/mod_s2s.lua	Sun Jun 17 20:02:40 2018 +0200
@@ -206,6 +206,9 @@
 			session.sendq = nil;
 		end
 
+		if session.resolver then
+			session.resolver._resolver:closeall()
+		end
 		session.resolver = nil;
 		session.ip_hosts = nil;
 		session.srv_hosts = nil;