Examples of the present invention present a method of determining the network connectivity technology being used in a network link. The method sends test packets from the router to an end device, such as a set-top box, and measures the latency in the received packets at the end device. The packets are gradually increased in size. The increasing packet size effectively results in increasing the load on the network link between the router and the end device. The latency characteristics vary as a function of packet size (representing increasing network load), and result in a signature or “fingerprint” for the network connectivity technology being used for the link, across the load cycle. The signature can be compared to predetermined models to identify the specific technology used. The technique can be enabled using software modules installed at the gateway/router and at the end-point, such as a set-top box.