In the realm of things that shouldn't have worked, I remember my brother in the early-mid 90s strung a telephone-grade wire around a house to directly connect two computers via their serial ports for serial-line IP (SLIP).
His best result was using one pair to connect send/receive lines like a null-modem. With XOFF/XON inband flow control and no grounding, he increased the serial port rates beyond what the modems of the day would achieve, and it worked. Our guess was that above a certain rate, it acted more like an AC transmission line and less like ground-referenced levels.
His best result was using one pair to connect send/receive lines like a null-modem. With XOFF/XON inband flow control and no grounding, he increased the serial port rates beyond what the modems of the day would achieve, and it worked. Our guess was that above a certain rate, it acted more like an AC transmission line and less like ground-referenced levels.