R7000 - Can't get into router log in page for setup

> Model: C7000|Nighthawk - AC1900 WiFi Cable Modem Router

> R7000 - Can't get into router log in page for setup

> We purchased a refurbished modem.

   What is it, a C7000, an R7000, or something else?

   "Can't" 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 with their actual results (error messages, LED
indicators, ...) can be more helpful than vague descriptions or
interpretations.

> [...] I have been trying to set it up as a 2nd router. [...]

   Why do you want two routers?  What is the first router?

> [...] it tells me [...]

   What/who tells you what, exactly?

   For a used device, a good start might be a settings reset.  Visit
http://netgear.com/support , put in your (actual) model number, and look
for Documentation.  Get the User Manual.  Look for "Factory Settings".

   If you still have problems, then a clear description of what you're
doing, and what happens when you do it, might help.  Some explanation of
what you're trying to accomplish might not hurt, either.

   Generally, you want one router, not two routers.  If you're trying to
extend the wireless-network coverage of your first router, then you
might want to configure a second router as a wireless access point (not
as a full-function router), and connect that to your original (and still
only) router.  (Look in its User Manual for "access point"?)