In reply to a post by 4Way:

why the same speedtests are slower with a direct connect than through the hub when the perceived wisdom is that this is the way to go to see whether the hub is the problem or the fibre/ont.

The fact that you're already getting 600+ Mbps on the BT router suggests there's nothing wrong with the service at BT's end. If you're not getting the same speed on a laptop/PC connected directly to the ONT then there is probably a limitation on the laptop somwhere, eg AV software, insufficient RAM/CPU etc. I wouldn't worry too much about this considering its normally your router which should be left connected to the ONT 24/7, not a PC. People usually test at the ONT with a PC if their router doesn't give them the expected speeds, not the other way around!

Thanks