Just a general question to satisfy my curiosity. Does Openreach overprovision the 900mbps speed profile so you can actually achieve 1000Mbps if you have a network card above 1Gbps as well as a Nokia ONT with the 10G ports?
No, that's not how it works. The actual connection supplied by Openreach is 1Gb however as by far the majority of customes only have 1Gb network cards that speed cannot be achieved the profile is capped by BT Wholesale at 900Mb.
