This means the Openreach modem can't detect your BT Business Hub. To fix this, try:
Checking the red end of your Ethernet cable is correctly plugged into the red socket called Fibre on the Business Hub.
Checking the other end of the Ethernet cable is correctly plugged into the LAN1 socket on the Openreach modem.
Disconnecting the modem's power cable - wait a few minutes & then reconnect. After a few more minutes the Power light should come on.
Restarting your Business Hub:
Press and release the Reset button on the back of the Business Hub.
Wait a few minutes for the Power, Broadband, and Internet lights to go steady green.
If they don't go steady green, see What do the lights mean on my BT Business Hub?
If your problem still isn't fixed and the LAN1 light is still off, have your computer switched on and get in touch by clicking the contact us link on this page.