Abstract: Disclosure is related to a modular network apparatus, and a system having multiple modular network apparatuses. One of the modular network apparatuses can be set as a master device. The master device includes a micro-controller, a network module for rendering network service, and an expansion interface unit. The master device provides at least one function module. The master device is connected to the other modular network apparatus which is set as a slave device via an expansion interface. Therefore the system can provide further function by the slave function. According to one embodiment, the master device and at least one slave device are connected via the expansion interface. Through this expansion interface such as a communication port, the system may deliver power signals, signals, or operating status. The master device and the slave device may also share the power supply, management scheme, and the interface.