What are the general interfaces on a network device and what are their purposes? Such as the protection of these interfaces?

Broadband cats, fiber optic terminals, routers, switches, HUB are network equipment, all of these devices have a power supply interface and LAN interface for connecting the power supply and network equipment and terminal equipment, broadband cats also have a telephone line interface for connecting the telephone line, fiber optic terminals have a fiber optic interface for connecting fiber optic, routers have a WAN interface for connecting broadband cats or fiber optic, these interfaces do not require special maintenance, only the telephone line interface should pay attention to lightning protection can be. These interfaces do not require special maintenance, only the telephone line interface should pay attention to lightning protection on it.