This is VERY Common.
I have this 12V / 34A power supply (came from Cisco router) and like to adjust the output to float a battery ( 13.8 V). Unfortunately the Vout adjustment shuts the power supply down at about 12.8V.
The power supply is a Switch-mode design (SMPS) and these supplies have an overvoltage trip point wired into the supply. Meanwell 12 V supplies have that trip point ~ 12.8 and their 13.8 VDC supplies have the trip point ~ 14.5 VDC.
Unless you are well versed in SMPS designs and IC usage, you will need a schematic. Since Cisco purchased this from Sony (OEM supplier) -- Cisco will not have the schematic!
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