[zig123]

Modem and a 2 router setup.

On router #1, ports for game ported to second router, using qos to prioritize gaming ports and the second router. Can a firmware like DDWRT do this? Maybe prioritize the second router by mac address?

For router 1, connect it via wan or lan? How does the second router need to be connected? Via wan or lan?

On router #2, accept all incoming port traffic and reroute the individual device ranges and ports. The first part I believe I understand, turning off the firewall or nerfing it somehow. Rerouting the device ranges and ports I am unsure of. Also would like qos to work on this one as well.

For the second router I plan on using netgear XR500 but I can replace it for another router. Can be interchangeable between router 1 or 2. Not sure what the other router I want to be. Prefer to support as many router firmwares as possible (openwrt, ddwrt, tomato, gargoyle, merlin) but pretty much any router firmware that can do what I listed in router #1 paragraph.

The goal is to game on router 2 with no qos (but able to use qos and work properly if necessary) with my ps5 connected to it and have router 1 prioritize router 2 so that the packets from router 2 go first at all times. I will connect the rest of the household devices on router 1. I don't want router 1 streaming and slowing my game down because the packets are trying to get ahead of my ps5 on router 2. But I also need qos to not be enabled on router 1.

[egc]

In general the XR500 is an excellent router and DDWRT compatible.

Without knowing the bandwith you have and the capabilities of the ISP router it is difficult to give advice how to setup your network

For some general information see the forum guidelines with helpful pointers about how to research your router, where and what firmware to download, where and how to post and many other helpful tips:
https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324087

Specific for R7800/XR500 see the link in my signature at the bottom