In one embodiment, a device in a network extracts words from traffic data for a particular endpoint node in the network. The device determines one or more topical categories associated with the particular endpoint node by applying a machine learning-based topical model to the extracted words. The device identifies one or more similar endpoint nodes in the network based on the determined one or more topical categories associated with the particular endpoint node and on one or more topical categories associated with the one or more similar endpoint nodes. The device determines a device type for the particular endpoint node based on a device type associated with the one or more similar endpoint nodes.