This KB article explains the difference between the behavior of the ntg3 driver, which is used in vSphere 6.5 with Broadcom NetXtreme 5717, 5718, 5719, 5720, 5725, and 5727 Gigabit Ethernet NICs, and the tg3 driver, which is used with those NICs in earlier versions of vSphere.
Broadcom NetXtreme 5717, 5718, 5719, 5720, 5725, and 5727 Gigabit Ethernet NICs use the non-volatile RAM (NVRAM) to configure some features, such as Wake-on-LAN (WOL). With the tg3 driver you can enable or disable WOL through the user interface of vSphere, without changing the configuration in the NVRAM of the NIC. Unlike tg3, the ntg3 driver respects the configuration in the NVRAM. Therefore, in vSphere 6.5, you are not able to change the WOL setting directly through the user interface.