<p>See our <a href="https://www.bt.com/help/broadband/bt-cloud/getting-set-up/download-or-access-files/how-do-i-download-files--folders-and-devices-from-bt-cloud-">help page</a> for further information.</p>
With the front of the router facing you, it's an indented button on the rear left of the unit about half way up. A short, positive press is all it should need.
I only learn by making mistakes and owning up to them - boy do I learn a lot!
