When I setup ESXI 6.5 I found one of my network cards was not found. I could see that ESXI was aware of it by listing the adapters from the command line:
lspci -v | grep -A1 -i eithernet
This solution will work but does require you to allow ESXI to use Community Supported VIB's. If your happy with this, here it goes:
Run this from the command line:
esxcli software acceptance set --level=CommunitySupported
You should then be told the host acceptance level has changed.
esxcli software vib install -d https://vibsdepot.v-front.de -n net55-r8168
Now reboot the host.
You should now see it under the physical NIC's.