[Lovejoy]

The options for the WAN are PPPoE, Dynamic IP or Static IP
The advice from TP-Link was for the WAN to be set as dynamic IP which then auto finds the settings from the ISP as the modem actually has all the PPPoE settings i.e. username password etc.

However I have just set it to PPPoE and inserted the settings but it wouldn't connect.

The bit that baffles me is that the router actually reads the settings from the modem which indicates that there is a router/modem connection but it doen't allow other data to pass. The router has a built firewall which I have disabled but there are also other settings which I have played with somewhat randomly. They are:-
Enable IP address filtering which is off but the sub options are allow/not allow packets not specified by rules.
Enable domain filtering (off)

I have assumed that with the firewall disabled that the rules will not apply
Enable MAC address filtering which is off but also has sub options to allow/not allow pc's with enabled rules to accese the internet.
If I go to the IP address filtering rules the default filtering rules are Deny the packets not specified by filtering rules