The WHW DC jack is 5.5mm external and 3mm pin diameter with output 12V 1.5A if you wish to extend it.
Which PSU do you have with your Whole Home discs?
We recently changed the PSU to be the same as the Home Hub 6A (but white). This has a longer cord length.
it says MU24-Y120150-82 I think! 🙂 The lead is fairly long, it's just for this one disk that I want to put up high (because the only other place is about 40cm form the ground, not ideal!