I'm in the same boat. Last Sunday, going fine, suddenly, no internet. I connect with just the DSL modem/router and it works fine. Back to router, doesnt' connect. I found if I did an ipconfig /release and then an ipconfig /renew, it would work but I had to do that every time I lost th4e connection. I called a tech friend and he said our ISP had changed somethings at their end.
Oh, well.