c7000 cable modem no longer connects to wired devices but does to wireless devices

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

   Is that accurate?  Not a C7000v2?  Look at the product label.

   Visit http://netgear.com/support , put in your (actual) model number,
and look for Documentation.  Get the User Manual.  Read.  Look for the
LED descriptions and "Troubleshoot".

> [...] Only wireless connections are working. [...]

   Which kind of "not working" is this?  "not working" 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.

> [...] No hardwire connected devices are getting connectivity [...]

   Regarding "not getting connectivity", see "not a useful problem
description [...]", above.

   What are your (unspecified) "hardwire connected devices"?  How many?
Connected directly to the C7000 LAN Ethernet ports?  Is any of them a
computer with a user-interface where you might be able to get some
information from it about its network connection?

> [...] All the lights are blinking on the ethernet cables [...]

   _Which_ "the lights", where?  At the LAN Ethernet ports on the C7000?
Color(s)?  "blinking" variably, showing activity?

> [...] I do see a couple not all hard wire connections show up on the
> UI [...]

   _Where_ "on the UI"?  Attached Devices report, or what?

> [...] I have room for 24 devices and ony 12 are connected. [...]

   I've never touched a C7000, so I know nothing, but when I look at the
pictures in the C7000 User Manual, I see only four LAN Ethernet ports.
Perhaps a more accurate equipment inventory, and a better description of
exactly what's connected to what would be helpful.  A bad cable between
your C7000 and your (apparent, unmentioned, unspecified) 24-port network
hub/switch (or some problem with that device) might explain many
potential problems.

   One obvious diagnostic step would be to connect a device (or more)
directly to the C7000, and see what happens.

> [...] I do a factory reset, do I have to go through the long and
> tedius phone call with Comcast [...]

   I don't see why you would.  If they liked it before (and if you
didn't fiddle with any MAC addresses), then they should still like it
after a settings reset.

> [...] and does it go back in firmware version [...]

   I wouldn't expect that.