As I couldn't find a clear, easy post I thought I'd put this here as it worked for me first time and will hopefully help someone.
Thank you and credit to Felix@Bigpipe for providing the following instructions:
To set up your router for UFB, follow the steps below:
Before you start, restore your router to factory defaults, either by holding the small reset button on the back for 30 seconds, or through the Management, Settings menu.
1. Connect your computer to a LAN port on the router Connect the WAN port on the router to the GE1 port on the ONT
2. Log in to the router at http://192.168.20.1 The default username and password are admin/admin
3. On the left panel click Advanced Setup, and then click WAN Service.
4. Tick the remove button on the preconfigured service, and then click the Remove button.
5. Click Layer 2 on the left pane, then click on ETH interface.
6. Tick the remove box, and then click the Remove button.
7. Click the Add button.
8. Select eth4/eth4, and click Apply/Save.
9. Click WAN service on the left panel.
10. Click the Add button.
11. Select eth4/eth4 from the drop down menu, and then click the Next button.
12. Select PPP over Ethernet (PPPoE)
13. Leave the service description at its default.
14. Set 802.1P Priority to -1 and the 802.1Q VLAN ID to -1. Click Next.
15. Enter PPP Username as Bigpipe, and PPP Password as Bigpipe.
16. Set the MTU to 1492
17. Ensure that “Enable IPv4 for this service” is ticked.
18. Click the Next button.
19. Ensure that ppp0.1 is in the left column, and click the Next button.
20. Again ensure that ppp0.1 is in the left column, and click the Next button.
21. Click the Apply/Save button.
22. Click Management from the left column, and then Reboot.
23. Click the Reboot button.
24. Your router will reboot, and after it has turned back on you should be able to connect to the internet.
Good luck, hope this post makes it easier for someone!
And if you're still having trouble contact firstname.lastname@example.org letting them know the status of the lights on the ONT: