Network Monitoring

Way more opions than stock firmware and relatively easy to configure

Advanced Port Scanner is a robust and easy to use free network scanner that finds open ports on network computers and retrieves versions of detected programs.

Fing is a network scanner app that provides device recognition, Wi-Fi monitoring, internet speed tests, and router security checks.

Powerful command-line packet analyzer.

ClearOS is a Linux based open-source network and gateway server for small organizations and distributed environments. It is also available in a paid Enterprise version.