Still need a modem? Ax4300

> Do I still need a modem to work with this ax4300?

   What is your "this ax4300"?  "AX4300" is a speed, not a model number.
Look for "Model" on the product label.  RAX45?

   With that datum in hand, you might try a radical concept which works
for some people:

      https://en.wikipedia.org/wiki/RTFM

   Visit http://netgear.com/support , put in your (actual) model number,
and look for Documentation.  Get the User Manual (at least).  Read.

   "still"?  Did you need a modem before?  With some other (unspecified)
router?  The non-psychics in your audience might know very little about
your Internet service, or what your (unspecified) ISP might require, or
what you were using before, with what.

   A RAX45 is a router, with no built-in modem.  If your service
requires a modem, then I'd expect your service with a RAX45 to require a
modem, too.