I had the same problem with a D-Link router and Century link a few months back. Century link tech support was able to see that it was not receiving my log in info. It was the router not sending ppoe user and password. Had a spare router that I could put on line quickly which proved it.
I would reset the router and reprogram it. Another thing is to make sure the modem is in bridge or pass through mode which it must be in for the router to handle ppoe.