Here is a nice protip from one of my readers, Peter, who recently came across an issue with an Intel x550 network adaptor and ESXi not listing any of the Multi-gigabit (2.5GbE or 5GbE) options even though his underlying physical network was setup as 2.5GbE, only 100MBps, 1GbE and 10GbE was available.

After a bit of trial/error, he discovered the solution was to update the inbox version of the Intel ixgben driver (1.7.1.44-1vmw.803.0.0.24022510) to the latest supported version for ESXi 8.x and he immediately saw the additional Multi-gigabit speeds as shown in his screenshot below:

Peter thought this might be worth sharing as others have also ran into this problem when using an Intel-based Network controller (82599, x520, x540, x550, x552 & x553) with Multi-gigabit physical networking.

To download the latest Intel ixgben (1.15), you will need Broadcom Support Portal (BSP) account that has an entitlement to a vSphere SKU (e.g. vSphere Enterprise Plus) and you can find the driver by navigating to MyDownloads->vSphere->(Select your SKU)->Drivers & Tools and then filter by ixgben and look for 1.15 as shown in the screenshot below:

After downloading the driver, you will need to unzip to access the ESXi Component (zip), which you can either install using vSphere Lifecycle Manager (vLCM) or directly on an ESXi host by uploading it to host and then running the following ESXCLI command:

esxcli software component apply -d /Intel-ixgben_1.15.1.0-1OEM.800.1.0.20613240_21375148.zip

Once the updated driver has been installed, reboot and you should now be able to select additional Multi-gigabit speeds!