Currently using the Router TD-W8980, so far a great router however there is a few firmware issues (Currently on the latest) i have noticed. I have CWMP disabled yet the port is still open and looking on the TP-Link forums this has been a issue since 2013.
The other issue i have noticed is that PPPoA doesn't have NAT but PPPoE does which i find strange as all the other routers i have had has a NAT option so it does seem strange.
I have also found that the Remote Management option even disabled is still accessible.
So there seems to be some security concerns. If you haven't already make sure for now that you setup a firewall rule to block access to the default CWMP port which is 7547 and change the username and password in the CWMP area even if its off. Then change the URL to https:\\127.0.0.1 . On top of this disable Connection Request Authentication by unchecking the box.
Thought i'd give everyone a heads up on this issue.
If you want to test it use the following
http://router_wan_ip:7547/tr069 default pass is the same as username which is admin.