A method of training a physical interface between a first device and a second device includes performing a first training of the physical interface by communicating with the second device by using a first candidate group of lanes from among a plurality of lanes; performing a second training of the physical interface by communicating with the second device by using a second candidate group of lanes from among the plurality of lanes, the second candidate group being different from the first candidate group; determining a lane group based on a result of the first training and a result of the second training; and setting the second device so that the determined lane group is used for the physical interface.