I'm interested in replacing this router as it is insufficient for my company usage. Anyone got any recommendation to replace this router? I've just tested with another existing Asus N14UHP which we are using and somehow it's not working with the existing Asus router. Thanks.

Have you reset the Asus Router and login to router web page to enter your maxis fiber username and password and install the wifi settings? I just switched to maxis from unifibiz 100 and have Asus RT86u with works well after resetting and entering the details.