Ok since some have just broken wifi, I would like you to try something, if it's a software issue, it should be fixed by downgrading or reflashing your firmware.
Here is a guide:
https://forum.xda-developers.com/t/asus-rog-phone-5-raw-firmware-flash-file-fastboot-ww-rom.4268331/Note ur data will be wiped, so back them up before.
Please report back if it worked or not, if it doesnt work, it's defnitely a hardware issue.
