Are you using the camera control tool to record? If yes, re install the control tool. What operating system have you update your PC to anyway? Does it still work on other PC?

Did you configure the camera through the app already? When you added the camera to the app the first time, it would ask you to create a username and password for the camera. Should use that to login.

If the WAN IPon the status page mismathc the IP on DDNS website, please test which one is your current Internet IP address. When connecting on VR400, open the google and just search for "my IP...

Try power cycling the modem and then login again. Make sure the PC is only connect to the 8961 modem via either wired or wireless.

How about the LED lights status when it disconnected? If DSL light is flashing or off, try this http://www.tp-link.com/en/faq-735.html If the DSL light is on solid at that time, login to D9's web UI...

As I know, the powerline wifi extender can work with the old password after upgrading the router. If do need to upgrade the password for the powerline extender, try this utility...