The Devolos are reporting the Theoretical LINK sped in one direction.
Actual speeds will be far less due to the half duplex nature of the adapters and noise on the electrical mains.
Techradar got speeds of 35MBps (280Mbps) one floor up with the cockpit showing a LINK speed of 1400Mbps for example, so the powerline speeds sound about right.
The powerline adapters are neither here or there, as you need to test with a gigabit enabled PC connected directly to the Hub as advised before.
It would be worth checking the Link speed in Windows network settings, and the PC's drivers are up to date and configured for auto negotiation. If the negotiated Link speed was not gigabit it would be 100Mbps, so you would not be able to achieve speeds of over 100Mbps.
The orange light on the PC does not indicate the Link is not gigabit at all, however, the Hub's LAN port lights being green does. (each vendor has their own scheme)
If you are not getting headline speeds then it does look like a faulty Hub as the Wireless is proving the internet connection if the speed is constant close to the router.