I'm trying to get VOIP to work on the thompson router while using my own custom router for wifi. The setup now is currently

AN-5506-04B [LAN 2] ------> [WAN] Asus RT-N14UHP
AN-5506-04B [LAN 3] ------> [WAN] Thompson Router

I've disabled wifi on the thompson router, can't seem to disable the PPPoE, can't find such a setting. The telephony screen shows that its not connected.