In my apartment we have an old LAN network where every room is reached by ONE ethernet cable that splits in 2 ethernet ports, the same happens to the hub where 6 cables arrive (one from each room) and each splits into 2 ethernet ports.

There are two problems from this:

  • Only one of the 2 ports is working for each cable
  • The connection is slow, it looks like it's maxing out the bandwidth of each cable

50Mb/s through cable connection, >300Mb/s if connected directly to the modem or via wifi (where the wifi signal is strong enough).

From my basic understanding of networking, the cables have been hard split (I can see it in the hub and disassembling the ports sockets in the rooms), to allow more devices on the same cable, but modern hardware is not able to recognise this automatically, hence only one of the ports is working and moreover the split cables have limited bandwidth.

My question is:
Can I rejoin the split cables using a LAN splitter like this splitter?
Or do I have rewire manually the cables to one port instead of 2?

Doing so would I be able to achieve Gigabit ethernet (with a gigabit router)?

  • What do you mean by "hard split"? How/in which order/arrangement are the wires of the cable in the wall connected to the sockets?
    – TJJ
    Feb 27, 2016 at 17:30

1 Answer 1


Rewire the cable at both ends using all 8 strands (http://logmett.com/index.php?/quick-tips/rj45-pinouts.html) and use a small gigabit hub to get more ports.

10/100 only requires 4 strands and they appear to have used an old trick of splitting the signal to enable two 10/100 connections on one cable.

Gigabit (10/1000) requires all 8 strands to be correctly wired at each end and cannot be split.

A quick and dirty fix could be made using powerline adapters, but no guarantees that it would work.


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