They should be compatible with each other. To set up the chromecast, you can follow the guide below. http://googlechromecast.com/how-set-up-google-chromecast/

Your computer has slient mode like the one on mobile phones? :confused:

The main router is secured with WPA-PSK/WPA2-PSK. If so, password of 28 digits should be OK. What's the firmware version of your WA701ND?

Do you know what protocol is used by Yawcam or Manycam? ONVIF and RTSP are not supported. It only supports http protocol.

As the picture below, can you change DSL Modulation Type to VDSL2 and check it will sync or not? Besides, contact your ISP to confirm if your line is VDSL nor not and check bandwidth given by your...

Did you login web interface locally or remotely? It cannot be ugpraded remotely. Login the web interface on the PC connected to LAN ports of W8961N and upgrade the firmware.