Loading an operating system of a diskless compute node using a single Virtual Protocol Interconnect (‘VPI’) adapter, including: setting, by a VPI firmware module during startup of the compute node, an operational mode of the VPI adapter to operate in accordance with a first data communications protocol, the VPI adapter including a preboot execution environment module that supports the first data communications protocol prior to loading an operating system and a driver for the first data communications protocol; retrieving, by the VPI firmware module from a network source via the VPI adapter in accordance with the first data communications protocol, the operating system and a driver for the second data communications protocol; and responsive to loading the operating system and the driver for the second data communications protocol, switching the operational mode of the VPI adapter to operate in accordance with the second data communications protocol.