Problem with power output of the NSM2 XW:

Hi everyone, I'm new here but I've been using OpenWrt for a while now, I recently bought an NSM2 but to my surprise it's from the XW hardware version (of the ones that use the Atheros AR9342) I was looking for information about that specific model. openwrt wiki and did not find anything, in the download section there is a firmware that seems to be yours (openwrt-18.06.0-rc2-ar71xx-generic-ubnt-nano-m-xw-squashfs-factory) I tried it and it works but when it comes to putting the power only with US it goes up to a maximum of 22 dBm which is not the maximum power of this equipment because with its Ubiquiti firmware it reaches 28 dBm, so please help me, maybe I'm wrong with firmware or such. From already thank you very much.