The default IP address is 192.168.254.254. You need to set an IP to your computer just as the following steps.
Set a fixed IP to your computer, such as 192.168.254.10. You can follow the guide to configure the fixed IP.
Connect your computer to the LAN port of MoCA adapter via ethernet cable.
Visit http://192.168.254.254, username is admin, password is gocoax.
Thanks that worked, just had to stop the ipv6 to connect automatically.