You cannot use the AX50 for voip. I called TPlink and they confirm even though there is selection in the menu for voip it does not work. I am using ONU to Asus router to maxis router to dect phone. The Asus does all the DHCP and the maxis router is purely for the voip. TPlink AX50 cannot be used for voip even though there is a selection in the menu. Asus routers lan 3 is always voip compatible.