OnLogic is a manufacturer of industrial computers. ML350G-10 is one of their mildly ruggedized models intended for use on desktop or mounted on a DIN rail. The model is still in production; the manufacturer's Web site has it starting at USD 1,753. Obviously, the device is priced first and foremost on parts binning, rather than on specifications. So when I saw one listed on eBay at USD 78, I wanted to check it out. But to be totally honest, I always liked how orange and silver go together, too, so that was an added attraction... 
The device I have runs on an Intel Pentium N4200 processor (quad-core, 1.1 GHz base, 2.5 GHz burst). This is the more upscale of the two processor options (the more basic one is a dual-core Celeron N3350). There is one RAM slot that accepts DDR3L memory. My unit came with a 4 GB module, the manufacturer says 8 GB is an option as well. The primary storage device is an mSATA drive (factory configurations start at 64 GB). My unit didn't come with a storage drive, so I reached into my storage closet and found a 16 GB Transcend drive that worked out quite nicely (more on that later). Wired networking is handled by a pair of Realtek RTL8111G controllers. Wireless networking can be added (again, more on that later). There are two DP ports providing video output and seven USB ports (four USB 2.0 on the back panel and two USB 3.2 Gen 1 and one USB-C on the front panel), so plugging in a monitor and a keyboard shouldn't be a problem.
Power-wise, the device expects 12 V / 3 A over a generic 5.5 mm barrel connector.
To open the device, you remove three screws located underneath Ethernet, USB, and DP ports (see photo above) and two more in the corners of the bottom panel on the opposite side of the device. Once that is done, you can lift the bottom panel out.
To install OpenWrt on the device, I wrote a squashfs-UEFI image onto an mSATA drive and installed that drive into the middle slot marked mSATA. Note that with this device, you must use UEFI firmware; the BIOS appears to have no option for legacy boot. Speaking of BIOS, it is unlocked and accessible by pressing Del on boot.
In its basic configuration, the device doesn't have any wireless hardware. However, it can be added. There are two mini-PCIe slots in addition to the one in which I installed the mSATA drive. The one on the right is marked mPCIe and intended for a wireless card. The one on the left, marked mPCIe / mSATA, appears to be capable of holding either a storage drive or a wireless card. There are four punch-out openings for external antennas in the back panel, so dual-band wireless appears to be a distinct possibility.
In a quick bidirectional iperf3 test (client on the LAN, server on the WAN), the device delivered 930 Mbps up / 930 Mbps down, which is basically Gigabit minus housekeeping traffic. Just for kicks, here's an htop screen during the iperf3 test:
My overall impression is, if you need a simple fanless Gigabit device that will run for a long time without complaining or quitting, this one just might be it...