ConnectX-2 and ESXi 6.5 slow speed

Hi,

I have ConnectX-2 card in my ESXi 6.5 server

Added this card to FreeNAS (VM) and OpenMediaVault (VM) as VMXNET3 adaptor

When i test the speed between the FreeNAS/OMV (VM) and Windows (PC) i get only 200-300 MBytes/sec

When i test the speed between the FreeNAS (VM) and OMV (VM) i get 4000-5000 MBytes/sec - on the same vSwitch

When i test the speed between the Windows (PC) and Windows (PC) i get only 900-1000 MBytes/sec - Result that i expected to be in ESXi

Tested speeds with iperf

What can be the problem? drivers?

By the way when i passthrough the card to FreeNAS, the FreeNAS doesn’t recognize it.

Thank you for help