2700 and 2500
The power consumption depends on loading, including USB and how many ethernet ports are connected, whether they are 100M or 1G, and how busy they are.
The 2500 and 2700 are labelled 0.1A at 230V, which corresponds to 23VA. For a fully loaded brick we have measured close to that.
However bear in mind that power (watts) and VA are not the same thing, due to the power factor. The FB2700 draws between approx 8 and 15W power depending on loading, the FB2500 between approx 7 and 12W.
The 2900 is rated at 15W.
Are rated at 20 watts.