Hi Rujag,
Both the MR57 and the MS125 supports PoE+ (802.3at), the supplied power is up to 30.8W, which doesn't means the AP will all the time consume full power. The consumption is negotiated depending on the current client needs. In the MR57 datasheet is a brief note. "Actual power consumption may vary depending on the AP usage."
It is normal to see less power consumed, the few times you will see all the power consumption is when the AP is running at full load.
https://documentation.meraki.com/MR/MR_Overview_and_Specifications/MR57_Datasheet
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