Nighthawk C7000v2

> I want to set up a router VPN but don't know if my Nighthawk C7000v2
> is compatable with a VPN or does the fact that it is a modem/router make
> it incomapatable with VPNs? [...]

   Pretty much, yes.  The firmware in a typical DOCSIS-compatible
modem+router is off-limits to the user.

      https://kb.netgear.com/000036375

> So far none of the VPN services that I have checked list my router.

   I'd expect that trend to continue.

   One possibility would be to configure your C7000v2 as a modem only
("bridge mode"), and get some VPN-compatible (separate) router to use
with it.

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual (at least).  Read.  Look for
"Connect Your Modem Router to a Router After Installation and
Activation".