There are two different device drivers for this nic card, the i40en and the i40e. The latest version of the driver for the i40en is 1.5.8 and it came out later than the 2.0.7 i40e driver
I am not even sure of the difference between the i40en and the i40e. This KB suggests that using the native mode driver is the way to go.
Does the "n" in i40en suggest it is the native mode driver?