Installing ESXi on a NUC with a 2.5 GB NIC

I am not a server guy. I’m barely a computer guy. I am an infrastructure guy. I know enough of the upper layers to make Layer 1 and Layer 2 work so my recent project to build a virtual environment for my home lab was a journey into the unknown for me. A journey that I thought was supposed to be smooth was turned into some movie-like adventure by something I got, that I didn’t even mean to get. What I ordered was an Intel NUC that happened to come with a 2.5 Gbps NIC.

I was more focused on memory and storage (and a power cord) than I was on the NIC because I never have needed more than 1 Gbps in my lab. When I went to install ESXi everything went as planned until halfway through the installation, I received the following error:

ESXi Network Adapter Error

I knew I had an adapter and knew it was plugged in. I could see the connection on my local switch and I could see the lights blinking on the box. The problem, as many others figured out, what that the ESXi installation package didn’t include the drivers for the 2.5 Gbps NIC. The drivers exist, but they aren’t packaged with the ISO from VMware. The solution is to “slipstream” the drivers and then it all works.

That’s great if you know what that means and how to do it, but if you are like me, the only slipstreaming you know about has to deal with cars on the road, not computers.

Hopefully, this is another instance where my pain can be useful for someone else.

Before You Start

I think a little different than most, so this list is meant to be followed in order. Personally, I like to make sure that all my tools are in order before going to find the files I am going to use, that way I can remember where I downloaded the files. With that being said, this is what you need to figure out before you start this adventure.

  • Windows laptop. This is required to create the ISO using PowerShell and PowerCLI. For whatever reason, using a different platform doesn’t work when it comes time to create the ISO, so find the Windows laptop now and start using that.
  • PowerShell 5.1. Not being a Windows user and haven’t ever used PowerShell before, this step stumped me. Also, the version number is important. If you try to use PowerShell 7.X it will fail because that version doesn’t support PowerCLI. Don’t ask me, I’m not a server guy, remember? Another thing I learned is Windows 10 has PowerShell 5.1 already, so DON’T go and download the latest version of PowerShell on your wife’s computer because you know she doesn’t use PowerShell so no reason why it would even be there. Then you have two versions of PowerShell (no problem) but trying to figure out which one is 5.1 and which one is 7.X is painful. Oh, and make sure you launch that thing in administrator mode, or else it fails.
  • Rufus. Rufus is a Windows version of Etcher (I think) but from everything I read, that is the tool you need. If your significant other is like mine, they probably don’t have a USB burner application on their computer so might as well install the one they talk about in the instructions. You can find Rufus here.
  • A USB drive, 4 GB or larger. If you are reading this you are probably staring at a USB drive with an ISO already installed that failed. That one will work, and if you use Rufus, you don’t even need to reformat it, the application will do it for you.

Time for Files

Full Disclosure here. I am going to link to a couple of different blogs that I used that help me through this. All the credit goes to these smart people, I am simply piggybacking off their work to bring it into a single document that I understand and can refer to in the future, should I find myself doing this again.

If you happened to download the latest ESXi installation file for a live install, that’s a shame. It also means you are exactly like me. Go back to the website and download the Offline Bundle zip file instead. This is the base image that allows you to slipstream in the drivers you need. Next, you are going to need the NIC drivers.

For that, I am going to send you to another blog written by Florian Grehl to read through their work. You can find that blog here. While Florian discusses a couple of different issues, we are most interested in the Net-Community-Driver under the “Update Bundle and Fling” section. Turns out a “Fling” is something that is from VMware and works but isn’t officially supported by VMware. Go ahead and download that driver.

Making The ISO

If you aren’t doing this on a Windows machine, now is the time to pack it all up (the ESXi offline bundle and the NIC driver) and move over to the Windows machine you have ready for this. Also, grab that USB stick with the ISO installed on it that didn’t work, you are going to need that.

For this next step, make sure you fire up Powershell 5.1 and MAKE SURE you run it as an Administrator. To determine what version of Powershell you are running, use this command.


Make sure you are in version 5.1 and then you are good to go to follow the instructions from a different blog by Guido Appenzeller that you can find here. The reason why Powershell 5.1 is important is that you need to install PowerCLI from VMware (step 1), and it won’t run on Powershell 7.X. Ask me how I figured that one out… If you are running Powershell 7, PowerCLI won’t install and that is a requirement. Guido’s blog is the part where you “slipstream” the driver into the ISO so it’s critical you follow his instructions. Don’t rush, take your time.

At the end, when it comes time to use Rufus, it is similar to Etcher but with more options to figure out. Select your USB drive, your newly created ISO file, and then select it. That part is a little wonky and might take you a couple of tries of clicking around to get it to register. It will work, the order of operations is critical to get Rufus to register that you have what you need. Once ready, it will ask you if you want to format the drive before flashing the new ISO (select yes and double-check you are indeed flashing the USB drive and not your hard drive), and then let it run. If you get stuck try this blog from Mike Tabor.

For me, it actually went faster than I thought it would, and I ended up flashing it again. No harm, but the finish was a little underwhelming for me.

Install ESXi on your NUC 11

Once Rufus is done, pull the USB and move back to your NUC. The installation won’t hang up with that pesky error that brought you here, and you will be on your way.

Special thanks to Florian Grehl, Guido Appenzeller, Mike Tabor, and especially William Lam from VMware for all of their work. My goal here wasn’t to take credit for their work and effort, simply just to package it in a format and flow that works for me. If it helps you out, great, but really they deserve all the credit.


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