You may have a look on this topic:
http://forum.mikrotik.com/t/routerboard-433ah-3v1-chipset-problem-ip175d/36800/1
Also, MT support said that is not possible revert IP175D features off without hardware modification… Im kinda suspect that some weird problems we have are cuz of that damn chip, but unfortunately we can’t switch dozens of RB. It’s frustrating.