A 4PON GPON OLT (4-Port Gigabit-Capable Passive Optical Network Optical Line Terminal) is a core central office device in fiber-optic access networks, equipped with 4 independent GPON service ports. It serves as the interface between the backbone network and the passive optical distribution network (ODN), realizing functions such as optical signal transmission, user access management, bandwidth allocation, and service aggregation. By connecting to passive optical splitters, each GPON port can support a large number of ONUs (Optical Network Units) with a typical splitting ratio of 1:64 or 1:128, enabling high-efficiency, long-distance (up to 20km) gigabit-level broadband access for end users.