The primary function of a Layer 3 switch is to forward data packets between different networks (inter-network routing). This includes routing traffic between different VLANs (Virtual Local Area Networks) or subnets within the same network, or connecting LANs in separate buildings or locations. Layer 3 switches operate at the network layer of the OSI model and have the ability to make routing decisions based on IP addresses, allowing for efficient and intelligent routing of traffic between different parts of a network. Providing wireless connectivity and securing the network from unauthorized access are typically not primary functions of a Layer 3 switch.