I recently got three of these Citrix CB-140 SD WAN devices to recycle but I decided to play with them a bit first. Open the hood and a SuperMicro motherboard is in there! It has a mSATA slot, the smallest SATA SSD drive I have ever seen, it literally is a thumbnail sized circuit board that plugs into a SATA port with two small power leads. Then a 16gb USB drive plugged into the USB header. Six total SATA ports. 8gb of unregistered ECC RAM. Seven 1gbps RJ45 network ports plus remote management. A quad core Intel Atom C2558 CPU @ 2.4ghz. Room for two 3.5" hard drives.
I upgraded the RAM to 16gb erased both drives, verified that the NICs actually work (those white chips are physical switches for detecting LAN cable disconnects, I had issues with those back on some older RiverBed appliances. I then was able to install both Windows 10 and then VMware ESXi v6.7.
I will probably end up selling these. Even though they are a tad bit too noisy to be in the living room as a media player; they would be a pretty energy efficient VMware server, Plex Server, FreeNAS, or PFSense Firewall.
