Ethernet unable to connect to the internet.

My self-built PC running both Windows 11 and Bazzite Linux has, in the last week, been unable to use ethernet at all. In Windows in the "Get Help" app I receive "No DCHP server was found," in Control Panel I can see the status of the ethernet as "No Internet access", though it seems to be connected to the network as IPV6 (which the ethernet does not use, to my knowledge) shows as "No network access".

In Bazzite, I went through an extensive command-line diagnosis process before trying to diagnose it on Windows. Both diagnoses seem to point towards the router being faulty and failing to give me an IP address, but apparently my housemate has managed to get their laptop working over ethernet when connected to the same cable in my room. I am double checking this as I am doubtful their laptop wasn't just using Wi-Fi, as they didn't turn it off to confirm.

I have power cycled my router and PC, performed a partial and a full network reset on Windows, reinstalled drivers, disabled and re-enabled the LAN port in the BIOS, manually set an IP address in Windows, all to no avail. I have tried more but I can't recall it all right now, though if you asked I'd probably remember. The only thing I haven't tried as far as I can tell is reinstalling either OS, and I would rather not try this anyway. Given that this issue is occurring on both Windows and Linux, I doubt that would fix anything.

The dual-boot setup has not given me a single issue in the 2 months I had Bazzite installed prior to this.

The lights on the port look fine (one solid, one blinking), the control panel's "Ethernet status" tells me it is somehow receiving and sending data packets at 1gb/s, and the cables are all relatively new. The sockets in the wall are barely half a year old, if that.

I am sick of this issue plaguing the back of my mind and just want it solved. I can't tell if this is a hardware or firmware issue on my end, or if it is an issue with the router. Does anyone have even the wildest of ideas what I can do to solve it?