I have tried ESXi 6 and because of unsupported LAN adapter (Realtek 8111G) I had to inject these two files with ESXi-Customizer from ESXi 5.1:
VMware_bootbank_net-r8169_6.011.00-2vmw.510.0.0.799733.vib
VMware_bootbank_net-r8168_8.013.00-3vmw.510.0.0.799733.vib
But at the yellow screen where it is loading drivers and services I get a PSOD something about this driver and IOMMU. I disabled Intel VT-d in BIOS and PSOD went away but when it is "Installing %" I get a "window" with something about an error inside these drivers where I can only press enter to reboot. I believe those drivers are not compatible with ESXi 6.
Any more clue about ESXi 6 and 5.5 and also 5.1 (also tried 5.1 by the way with same situation then with 5.5).
Thanks so far!