Some electricians will lazily splice in the wall an steal 2 pairs for another phone jack, like the guy above was saying. It’s very annoying, not exactly common, but does happen.
Though typically if that’s the case you’ll have multiple rj11 heads on the same wire at the head end.
Your phone lines were cat3.
You can technically get 10mbps, or in short runs, 100 mbps. Most NICs don’t even negotiate 10baseT.
And hence, why it wasn’t working.
Some electricians will lazily splice in the wall an steal 2 pairs for another phone jack, like the guy above was saying. It’s very annoying, not exactly common, but does happen.
Though typically if that’s the case you’ll have multiple rj11 heads on the same wire at the head end.