Just to pop in to clarify, that PPPoA isn't ADSL. It's Point to Point Protocol over ATM - without the technicalities involved, it basically means routing packets from the Ethernet network (local LAN) using IP (hence why you have a router) and sending it over the telephony network (the ATM bit), as the point of a router is to transport data between different networks as Ethernet cannot be broadcast through routers… la di da da… going slightly off topic but...
PPPoE is Point to Point Protocol over Ethernet - you need this when sending the packets from the router to a separate modem that is connected to Ethernet - such as a FTTP which uses the Openreach Fibre ONT to send on the packets instead of being directly connected to the router.
So PPPoA just basically means over the telephony network, meaning in this case, DSL of any kind that uses that grey RJ11 port. Anything needing to use an external 'modem' or network terminal would use PPPoE as it transports over the Ethernet away from the router and is picked up by the other device over Ethernet (using Ethernet frames).
Not directly linked to ADSL specifically, but you could say, xDSL I suppose.
