This issue can occur after adding a new NIC or replacing a NIC on your ESXi/ESX hosts. Contact the hardware vendor in order for the ESXi host to recognize the NICs again.
Start by checking the firmware and hardware compatibility with the hardware vendor. After updating the firmware, to troubleshoot NIC issues further:
- To determine if the hardware is seeing the new NIC devices, run the command:
lspci -v | grep -A1 -i ethernet
Note: If this command sees the NICs, but the esxcli network nic list command does not, the NICs still are not presented to the ESXi host. Contact the hardware vendor and follow the next steps.
- Check the driver used for the NIC is up to date: Determining Network/Storage firmware and driver version in ESXi
- Update network NIC driver per the Hardware Compatibility List: How to download and install async drivers in ESXi
- Check that the NIC is not listed as a pass through device. Check Passthrough for a Network Device on a Host
- Check ESXi logs (vmkernel, vobd, or var/log/boot) for possible clues on why the NIC did not load for ESXi.
Note: A hardware vendor may have a specific process or script that must be run to update or install a driver/firmware. Follow the hardware vendor's recommendations for installation.