Access a camera outside my router's IP range

> We installed a new Wifi Router Netgear Nighthawk R7000 in our office.
   Why?  Better wireless coverage, or some other reason?

> We switched internet provider and we needed to buy our own router.

> This gave us a new IP Range 10.0.0.x for our internal setup, so I went
> through changing hosts file, printer IP addresses all over the place.

   Probably the wrong approach.

> too late, it's done.

> Our setup is Modem > Nighthawk > big switch > [...]

   What is "Modem"?  If it's actually a modem+router (which seems
likely, if the R7000 chose "a new IP Range 10.0.0.x for our internal
setup") then you might have saved some effort and difficulty by
configuring the R7000 as a wireless access point.  Cascading multiple
routers can cause multiple problems, such as this one.
> Modem is Spectrum Internet Cable modem, the installer put it in bridge mode

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual.  Look for "Use the Router as a
Wireless Access Point".  That should put everything onto one big
(192.168.1.*) LAN, as before.

> I wanted to do that at first, but Spectrum does not grant access to log into their modem/router. So the only solution was to have our own router.

> I read that you cannot simply access a device outside the router's ip
> range [...]

   Where, exactly, did you read what, exactly?

> On one of a dozen forums I researched before posting my question here.

   If you insist on having two routers (hence two subnets), then there
are ways (not very far from "simply") to make that work.  For example:

      https://community.netgear.com/t5/x/x/m-p/1644757
      https://community.netgear.com/t5/x/x/m-p/1558939

> Thanks, we have only one router

But configuring the R7000 as a WAP (and reverting all your IP address
changes) might be a better approach.

> [...] I think that IP is set on the camera itself.

   If so, and if you want to use it on some other subnet, then you'd
need to reconfigure the camera.  If it's simply connecting to the old
"Modem[+router?]", and getting its address from (the DHCP server on)
that router, then you may or may not need to fiddle with it.

> Thanks, I was able to factory reset the camera just now and it got a new IP address in my 10.0.0.x range. So everything works fine! 

> [...] I run out of ideas!

   Not soon enough?

> Thanks for your help!