The password you created is the password to let you login to your router, it is different from the wi-fi's password. The password on the bottom of the router is the default wifi password. You can...

8961 cannot work as a wireless router, which means 8961 cannot meet your request.

Hello, you can try to modify the MTU value on your PC. You can type the command in the screenshot.

No, VR900v(DE) is a Deutsch version VDSL/ADSL router, it only support Annex B ADSL line and it is not possible to run on annex A. But it support both annex A/B VDSL line.

I think you have bought a wrong product. As far as I known, D9 do not support VOIP function, but you can use some VOIP app instead.

This should work. The LAN ports of D7 can work as a switch.