public function shutdown(): NetworkInterface
    {
        foreach ($this->processes as $process) {
            $process[self::COMPONENT]->shutdown();
        }

        // explicitly destroy the $connections
        foreach ($this->connections as $connection) {
            $connection = null;
        }

        $this->graph = null;
        $this->processes = [];
        $this->startupDate = null;
        $this->connections = [];

        return $this;
    }