Shield101 wrote

Sound related to your network topology.
What's the firmware version and hardware version of your router ?
How about the lights on the router when one device plug into the LAN port? Have you changed another cable to have a try?
In my opinion, you can check the IP address when the PC or Xbox plug into the router first

I have a similar issue to this. I have a TP-Link Archer C5 router. One of the ethernet network ports is plugged in to an USB-C dongle that also accepts power. The dongle is connected to a macbook. Out of the blue, my internet went out, meaning my router reported no internet to all of the devices, both wired and wireless. This persisted through a full router reset.

After some troubleshooting I found out unplugging the ethernet cable going to the dongle caused the internet to return, and plugging in the wired ethernet connection to the dongle disabled the internet.

I tested plugging/unplugging all the cables to the dongle and unplugging it from the macbook. For some reason, that seemed to fix the internet connection. I'm not sure if the power supply to the dongle was somehow feeding power or other signal back to the router, causing some kind of failure. Or maybe the dongle wasn't related at all and it was just a coincidence. I was able to reliably reproduce plugging in the ethernet cable to dongle caused the internet to go out (as reported by the router), and unplugging it caused the internet to return, without changing any other settings.

During the entire outage, I was always able to plug a laptop directly into the ethernet to my modem and get internet, and I confirmed with my ISP there were no issues on their end.

Could a faulty dongle that accepts USB-C power send a bad power-over-ethernet signal back to a router, causing a malfunction? Could this also be something specific to TP-Link / Archer routers?