How to open a port on my pc.

> How to open a port on my pc.

   Why?

   To the extent that "open a port" makes any sense, it would apply to
your router, not to your (unspecified) "my pc".

> [...] Orb router plugged into isp's Hitron Router. [...]

   Not a very detailed description of "isp's Hitron Router".  Has it a
model number?  Why two routers?

   Port forwarding tends to work better when only one router is
involved.

   If your "isp's Hitron Router" has a modem-only ("bridge") mode, then
I'd guess that you'd be able to configure it that way, and use the RBR20
as your one router.

   If the router section of your "isp's Hitron Router" can't be
disabled/bypassed, then it should be possible to configure the RBR20 as
a wireless access point, and use your "isp's Hitron Router" as your
router.  In which case, you'd configure the port forwarding on the

"isp's Hitron Router".

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual (at least).  Read.  Look for
"Use the router as a WiFi access point".

      https://kb.netgear.com/26765

> [...] Been trying for 3 hours to figure this out. [...]

   The length of time spent is much less interesting than what you did
during it, and what happened when you did whatever you did.

   For the usual problems with port forwarding, see:

      https://community.netgear.com/t5/x/x/m-p/1859106