1. Dell 11. Gen are not certified for ESXi 6.7. You cant perform a fresh install from scratch... you have upgrade from previous 6.x right?
Last official supportet version is 6.0uX for R610. We have 6.5 latest running (not supportet) on them.
If you have a Dell x520 and using the Dell Custom ESXi Image iam pretty sure it comes with the right driver. If not... just take a look to VMware Compatibility Guide - I/O Device Search find your card, press the + sign and follow the link with the right version. It will tell you if the driver comes with ESXi or 3rd. Party and present the download link.
Can you proof that the card is in working conditions?
We are a dell shop and use dozen of 82599 and 510 and maybe x520 (we switch later to broadcoms) but i cant remember if you can see an additional NIC within iDRAC/OMSA. For sure you will see the Cards in newer generations of Dell Poweredge. I will check this out.
Within ESXi. If the card register on the server during startup it will be visible when running "lspci" from command line. If you use | grep -i intel or x520. Example:
[root@esx-node-05:~] lspci -vv | grep -i Gigabit
0000:04:00.0 Network controller Ethernet controller: Intel(R) 82599 10 Gigabit Dual Port Network Connection [vmnic4]
0000:04:00.1 Network controller Ethernet controller: Intel(R) 82599 10 Gigabit Dual Port Network Connection [vmnic5]
As long as lspci doesnt show the card the x520 isnt working in the PCI slot youre using. If you see the card.... get the PCIID and VendorID and we will find the right driver. The X520 is not a new card so iam pretty sure that the driver must already into the Dell 6.5u3 ISO Image.
Now disable the PCI Passtrough Feature for that PCI/BUS Device. You have remove that device from the ESXi OS and prepare it to add it directly to a VM for special purpose. You can use it for ESX or for VM.. but not both at same time!
Was there another card into that slot prior?
Click "Edit settings" on the specific VM and try to add a PCI Device. From the dropdown menu select your X520 PCI Card.
WHY you ask to make the Card usable under ESXi when you not want to use it for ESXi? *ggggrrrrrrr*
Any way.. whats the reason to bypass the NIC into the VM instead of using it as a Uplink on a vSwitch together with a normal VM Portgroup which is used by a vNIC?