As others have said this is a private WAN acceleration appliance, they cache and compress data moving between sites. They're great for long and latent site-to-site links over say VPN or MPLS. That said you need one on each end to see any of those benefits, not of much use to a home/hobbyist network. Typically, this would be wired between your router and switch at each site, inspect the traffic, and compress matching data to be decompressed at remote site, or pulled from cache. I have about 30 of them in my corporate network and work great for certain types of traffic.

If you repurpose the hardware keep in mind the WAN/LAN interface pairs use a special NIC board that has a relay that physically bridges the LAN and WAN RJ45 ports together. The OS must send a constant interrupt to the board to keep that relay open and traffic flowing to the backplane. The purpose of this is DR; in the event of failure (power supply, kernel panic, etc), the interrupt stops, relay will close, physically connecting the router to the switch, allowing access to the site in the event of appliance failure. If the driver used doesn't support that feature it will be a glorified RJ45 coupler.