workaround for #1224

src/server/ua_services_securechannel.c

@@ -54,4 +54,5 @@ Service_CloseSecureChannel(UA_Server *server, UA_SecureChannel *channel) {
     UA_LOG_INFO_CHANNEL(server->config.logger, channel, "CloseSecureChannel");
     UA_SecureChannelManager_close(&server->secureChannelManager,
                                   channel->securityToken.channelId);
+    channel->connection->close(channel->connection);
 }