If you are running ESXi 6.0/6.5 and using a Intel X710 network adapter, the network card port may stop forwarding packets, if you are using the native driver (i40en). I customer using both Dell, HPE and Lenovo servers where I have seee this problem. This is a huge problem.
The is due to a new function in the driver called "Malicious Driver Detection" or MDD for short.
I the vmkernet.log file you will see, this lines.
i40en: i40en_HandleMddEvent:6495: Malicious Driver Detection event 0x02 on TX queue 0 PF number 0x00 VF number 0x00 i40en: i40en_HandleMddEvent:6521: TX driver issue detected, PF reset issued
The problem is fixed in ESXi 6.7 that has a new driver version 1.7.1.
The workaround is to uninstall og disable the native driver "i40en" and have a working version or the Linux style driver installed "i40e".
I really hopes that Intel will fix this now, the article from the forum is dated May 23th of 2018.
Update (14th July 2018)
There is a known issue with the i40e driver versions up to 2.0.6, so you should use 2.0.7 or newer. See VMware KB: https://kb.vmware.com/s/article/2126909