This is the new BT Smart Hub X that I will be using for my Ultrafast Broadband trial. The trial service that BT is providing is based on G.fast technology. BT’s Fibre-optic cables run all the way to a cabinet in the street (fibre to the cabinet or FTTC). The cabinet is then connected to homes with regular copper wires. BT’s G.fast technology reuses the existing copper wires and offers speeds of up to 330Mbps.
As the G.Fast service is very fast (290Mbps – 330Mbps), BT are providing the Smart Hub X which is rated for the throughput of the service. Some cheaper routers were designed for older FTTC and only have a 100MBps WAN port, which if used with the G.Fast will be limited to a maximum of 100Mbps.
The back of the Smart Hub X, showing four Gigabit Ethernet ports and one USB port (most likely USB2).
These are the setup instructions that are printed inside of the BT Smart Hub X packaging.
Note the use of the G.Fast filter, even if you a newer phone socket. (The instructions are confusing. I have a new G.Fast faceplate fitted and don’t need to use the G.Fast (dangly) filter). Before the trial a BT engineer will visit each customer premises in order to “install” the service. The service can only be installed at the phone line’s master socket. The engineer will replace the face plate on the master socket for a new one that has both a standard BT socket and an RJ11 socket to connect to the Smart Hub X:
Ellis Karim's Blog 
I’m unclear on the dangly filter vs the new Service Specific Face Plate. If BT will instal a G.Fast SSFP then why does the documentation say to use a retrograde dangly filter?
The instructions are confusing. If you have a new G.Fast faceplate, you don’t need to use the G.Fast (dangly) filter.