Same barrel / jack size is used across recent Openreach ONT whether Huawei or Nokia, ADTRAN (or indeed the long deceased ECI): 2.1mm (inner) x 5.5mm (outer) x 9.5mm (long). Positive tip/centre conductor. 12v supply.
See SIN, page 27:
https://www.openreach.co.uk/cpportal/content/dam/cpp...
That's perfect thanks a lot!
Make sure you can buck/boost the USB to 12v otherwise you’re in trouble. Also need around 5w on quiescent / steady state and bit more on start up.
Yeh, I think I have headroom, the port is primarily for external drives. At one point, I accidentally used the wrong adapter with the router that was a good 10W less than the proper one (lower current rating, same voltage) without any issues -- implying the over-speced adapter is probably linked to the need to attach devices to it (would also align with it using USB-C with PD).