have you solved your problem? We have the same.
What did you do? Have you update the i40n driver?
I found this:
Thanx for your support
Check if you experience the same issue switching over to the legacy i40e driver:
Be sure that you have the two drivers otherwise you will need to download the i40e from the HCL
#esxcli software vib list | grep -i i40
Then you should disable the i40en module with the following command:
#esxcli system module set --enabled=false --module=i40en
#esxcli system module set --enabled=true --module=i40e
Then reboot the ESXi host.
If you experience the same issue using the i40e driver, isolate it by moving one vmnic at the time to active, and see which one is dropping packets. You might want to have a look at that physical switchport and cable connected to this particular vmnic.
Hope it helps, good luck!
in these days I can't test anyway the problem because the server is already installed to the end user.
But I'll try to follow both the solutions
Thanks and keep update