Zaroo

As of right now, I am trying to figure out how to check the logs on the Hitron interface. There was something called DOCSIS event logs, but it didn't seem to show network related activity in comparison to DumaOS. 

Okay, I am going to send it to you via message. Actually, look at the 2nd one I am about to send you. If you don't mind please, sir. About 10 minutes later, I got disconnected from the game entirely and the dumaos interface said I was no longer connected to my router. I made some qos changes as I was contacting servers to try to mitigate the anticipated disconnection. Little behold, that second unknown device appeared as well. 

That's interesting, clearly a lot of people similarly curious too.  Did you notice any issues with service/performance around the time this entry was logged? Or were you just curious?

Okay. I won't turn on my PS5 today and will send you an additional log this afternoon. Apparently my time zone are settings are in DumaOS are not accurate in comparison to the times in the log. I am going to send you a log of today in the mean time. I got to go to work. Thanks for the feedback.

Okay. My NAT type as been fine. I don't understand why I all of a sudden experiencing issues with it. I'll send it when it occurs again. Thanks

I can't see why that would have made any difference to the IP address amount of any devices, did it at least get rid of the unknown device?
The ISP modem should either be in bridge mode or have the XR WAN IP in its DMZ ideally.

For router MAC address select Use Default Address, apply, reboot from the interface, wait 2 minutes then delete the device and see if it reappears. Given it's just the router though it won't cause you any problems and isn't a risk

Does it get an IP address at all or is it just the MAC address that appears? Check the MAC address, does it match the MAC address of the actual router?

Is your network simply setup as Internet -> Modem -> R2 -> Connected devices? If not, what's your exact physical setup?

Are you using a Netgear extender/switch/AP or anything else connected to the XR? Set a reserved IP for the PC in LAN Settings and then reboot the router, it will then only have that IP from then on