The replacement cable is now wired around the floor, wrapped around the door frames, and a hole drilled through it to the mdeom.
The hole is a bit sloppy and there's a bit of excess cable, but christ it looks better than it did previously, that's for sure.
So a year or so back I upgraded to a new internet/TV package that was Quite A Steal™️ at the time.
The schmuck who wired the ethernet cables did it in a sloppy, "get it done so I can get out of here" sort of way: Sticking it on the ceiling, leaving giant gaps near corners, and wrapping it around the door jamb instead of drilling a hole through it.
That is likely the reason why my internet stopped working at 1:30AM last night.