Using a Nighthawk AC1900 exclusively as a router

[kentonsanders]

I have a Nighthawk AC1900 cable modem router that I like very much.  I wish to hook my phone line up through Spectrum.  To do this Spectrum requires use of their cable modem.  Thus, I would like to use their cable modem and continue using the Nighthawk AC1900 router capabilities.  Is this possible, and if so, what setup changes and connections are necessary.  Can you steer me to a description, manual or YouTube for this?

[antinode]

> I have a Nighthawk AC1900 cable modem router [...]

   "AC1900" is a speed, not a model number.  Look for "Model" on the
product label.

> [...] Spectrum requires use of their cable modem. [...]

   Has _it_ a maker and model number?

> [...] I would like to use their cable modem and continue using the
> Nighthawk AC1900 router capabilities. Is this possible, [...]

   Assuming that your "a Nighthawk AC1900 cable modem router" lacks a
WAN/Internet Ethernet port, then no.

   What, exactly, does "router capabilities" mean to you?  It should be
possible to use a model Cxxxx as a wireless access point.  See, for
example:

      https://community.netgear.com/t5/x/x/m-p/1463500

That's written for a Netgear C6300-as-WAP, but the steps are about the
same for any other router (any make/model) which lacks a one-step WAP
option.  (Especially similar for another Netgear Cxxxx.)