This is my first time here, and if this isn't the right place for this question, my apologies. Please direct me to the right place.

In order to get a wired LAN connection to a desktop computer and a printer using the one Ethernet jack available in that room (due to home wiring), I am interested in "splitting" the RJ45's cable into two different "lines" using this splitter on Amazon. Many people (and apparently the maker of this adapter) seem to believe you can functionally use only 4 wires inside a RJ45 cable to sustain a reliable LAN connection, which would allow you to use one RJ45 cable to be used as "two" cables using this adapter. My understanding is you use two Ethernet patch cables to go from two ports on a router into this adapter which uses 4 wires of the 8 wire total RJ45 cable for each connection, and then put the same adapter on the other end of the line and "split" the signals back out into two RJ45 jacks on the adapter so two Ethernet devices can plug in.

Or at least that's what I think.

First off, is my idealism valid, or is this actually nothing but a signal combiner? Can you indeed establish an Ethernet LAN connection using 4 wires of a RJ45 cable instead of 8?

Secondly, if this is possible, how much network performance would the devices lose due to less copper as compared to a dedicated Ethernet cable? In my case, I am running a 50' run, which (I think) is a decent amount of cable, but isn't a stretch to the 100 meter standard.

  • This seems to be regarding home networking, which is off-topic here. Dec 6, 2013 at 3:07
  • As Mike has said, this product appears to be targeted at consumers and is out of scope. That said, yes you can do this in theory as 10BASE-T and 100BASE-TX both only use two pairs of copper. In practice, I would not recommend it, as the only two environments I have seen something similar done (split a single 4-pair wire to provide two network ports) have both had issues, although this was done on a bigger scale than just one run at both sites.
    – YLearn
    Dec 6, 2013 at 3:41
  • 1
    The SuperUser stack seems to have this covered under splitting ethernet cable Dec 6, 2013 at 14:37
  • Sorry guys.. didn't see that posted there. My bad~ Dec 6, 2013 at 17:41

1 Answer 1


10 and 100 need only 2 pairs (pins 1-2-3-6) Gig needs all 4.

This adapter brings 4-5-7-8 to the second port's 1-2-3-6. This is, technically, a spec violation, but over short distances, it does work.

(it's just like a line-1, line-2 phone splitter.)

  • Thanks for the answer @Ricky, our internet is only about 3MBPS total (WISP) so the most bandwidth going over the network is maybe more near 100MBPS LAN File Transfers.. you don't think 50' is that far do you? Dec 6, 2013 at 17:43

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