Cable Modem

> [...] I have another ethernet cable in port 2 going to my Nighthawk
> X6S (model: R8000P). It is not getting a connection to the internet.
> [...]

   Ok.  Visit http://netgear.com/support , put in your model number, and
look for Documentation.  Get the User Manual.  Read. Look for "Rear
Panel" and "LAN ports". (Further reading might be helpful, too.)

   The CM1200 is a modem, not a modm+router.  With typical residential
service from your ISP, which allows you one external IP address,
connecting multiple client devices requires the use of a (NAT) router,
not only a modem.

   Connect (only) a router to the CM1200, and connect your client
devices to that router.

> [...] I still cannot log into the modem with the default username &
> password.

   Which "the default username & password" did you use?

   "cannot" is not a useful problem description.  It does not say what
you did.  It does not say what happened when you did it.  As usual,
showing actual actions (commands) with their actual results (error
messages, LED indicators, ...) can be more helpful than vague
descriptions or interpretations.