Due to the space limitation of the conduit, I ran a single cable from the switch to my room, and intended to run 2 separate fast Ethernet lines on it (4 wires each). I bought this thing from China for as cheap as $0.23, and initially thought that it split a single 8-pin connector to 2x 4-pin ones:

enter image description here

I don't understand much Chinese language, but I've talked with the seller, and he said that it could not connect 2 devices to the Internet at the same time, and the example usage was using a single source port to run 2 cables to 2 rooms, then the user could move a single laptop between 2 rooms.

Now that I've got a sample unit. Let's call the source port A, and the (split) destination ports B and C. With my network testing tool, I found that pin A1 connects to both B1 and C1, A2 to both B2 and C2... and so on up to A8/B8/C8. The signal received on a port is repeated on the other ports.

Of course I can still use it for my purpose by using 2 units and wire them correctly on both ends. But now I am wondering if I can use it as a network hub? Living in an era when hubs were extinct, I have never seen a hub before and I am curious.

Note that this device is simply a passive adapter which splits signal by re-wiring, with no processor inside.

  • Unfortunately, questions about home networking and consumer-grade devices are explicitly off-topic here. You could try to ask this question on Super User. – Ron Maupin Oct 9 '19 at 13:40


Repeater hubs and switches require power. If there's no power supply that can't be an active device.

The photo says "ONE AT A TIME", so you can't use both ports jacks simultaneously.

Get a small switch, they're cheap.

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  • With all 8 wires (or pins) connected from one port to the other 2, all signal received will be split and sent to 2 destinations at the same time. It sounds exactly like a hub's functionality to me. Is there some technical issue that prevents it from working as a hub? – Livy Oct 9 '19 at 10:54
  • I do some hardware selling in my spared time, so I have a lot of computer and network hardware including switches. This question is just for the sake of studying and I can have some fun if that thing can be used as a hub. Playing around with low-end devices is my joy. Maybe I'll assemble 3 computers, boot them up and test it myself. I doubt what the seller said. – Livy Oct 9 '19 at 11:01
  • 2
    "It sounds exactly like a hub's functionality to me." No. A hub (actively) repeats a signal received on one port out of all the other ports. Only one port can receive and all others transmit. It doesn't simply cross all wires. Crosswiring more than two Ethernet ports cannot work. For details, check out IEEE 802.3 Clauses 9 and 27. – Zac67 Oct 9 '19 at 11:44

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