Setting up second router

> [...] my old R6300 [...]

> Model: R6300v2|AC1750 Dual Band Gigabit router, [...]

   R6300[v1] or R6300v2?  Look at the product label.  Firmware version?

> [...] I set a static IP for my R6300 on the XR500 [...]

   No, you didn't.

   Terminology: A "static" address is configured on the device itself.
What you configure on a (DHCP server on a) router is a reserved dynamic
address, not a static address.  (Either way should give a device a
reliable/fixed address, but it's nice to know what's actually happening.
Using static addresses requires more care in the configuration of the
DHCP server.)

   So, what, exactly, did you do?  As usual, showing actual actions
(commands) with their actual results (error messages, LED indicators,
...) can be more helpful than vague descriptions or interpretations.

> [...] The two routers are connected by a 25 foot Ethernet cord across
> two ends of my house. [...]

   If a device has different types of Ethernet ports, then "connected to
device" is not enough detail.

> [...] I want to keep both in router mode and I don't want AP mode,
> [...]

   Why, exactly?  This sounds like a fundamentally bad decision.

> [...] i like to use the Ports on my second router for better
> connection and it caused problems with gaming when I had the second
> router in AP mode. [...]

   How, exactly, did you "[have] the second router in AP mode"?

   "caused problems" is not a very detailed description of anything.
I'd expect more problems (including "double NAT") if you cascaded two
routers.

> [...] I read online [...]

   Thanks for the helpful link(s).

> [...] that I am supposed to disable DHCP on the second router or it
> would cause problems. [...]

   That would depend of what you're doing and with what you're doing it.
An R6300v2 has an Access Point Mode, which would do that automatically.
If you have an R6300[v1], then you might need to do that manually, as
_part_of_ its configuration as a WAP.

> [...] Am i supposed to input anything else into the internet settings
> of the R6300 after disabling DHCP? [...]

   Yup, if you want to use it as a WAP.

> [...] R6300 assigns IP in the range of 10.0.0.x and the XR500 sets IP
> in 192.168.1.x, so do I even need to disable DHCP on the secondary
> router?

   If you have cascaded two routers, with two different LAN subnets,
then you'd probably want a DHCP server on both LAN segments/subnets.

> [...] Tried bridge mode and AP mode, both sucked. [...]

   Bridge mode would involve a wireless connection between these
devices, not an Ethernet cable.  I don't see how that would apply.  So
far, it's not clear how you did "AP mode".  As a problem description,
"sucked" is about as useful as "caused problems".  That is, not.

> [...] Trying to keep it in router mode. [...]

   An actual reason might be nice to have.

   My advice for an R6300v2 would be to visit
http://netgear.com/support , put in your model number, and look for
Documentation.  Get the User Manual.  Read.  Look for "Wireless Access
Point (AP)".

   For an R6300[v1] which (I assume) lacks such a one-step option,
there's a step-by step here:

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

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

   Note that that scheme leaves the WAN/Internet port on the
router-as-WAP unconnected.  (A WAP is all-LAN.  A model with the
one-step WAP option effectively reconfigures its WAN/Internet port as
another LAN port.  Without the one-step WAP option, you need to use only
the LAN ports.)