Router is a layer 3 or 4 device if your ans is layer 3 then?

A router is primarily considered a Layer 3 device in the OSI model because it operates at the network layer, where it manages packet forwarding and routing based on IP addresses. It determines the best path for data packets to travel across networks and can connect different network segments. While it can also handle some Layer 4 functions, like managing TCP/UDP ports for certain protocols, its core function is focused on Layer 3 operations.