DG-GR6821AC is based on the stable and mature GPON and Gigabit EPON technology, it is highly reliable and easy to maintain, with guaranteed QoS, and fully compliant to IEEE 802.3ah EPON standards and ITU-T G.984.x which has high performance/price ratio. It supports NAT/firewall and the layer3 routing functions as well. It converts the fiber optic signal into the electric signal at the user side and enables reliable Fiber Optic Ethernet services to business and residential users through fiber-based network infrastructure. It terminates the PON on user side to provide high speed data services to the user. DG-GR6821AC is a dual mode ONT working on both GPON and Gigabit EPON technology which can detect and exchange PON mode automatically.