Running 2 ethernet connection over single CAT-5e cable

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I already have an existing network cable wired from my router to my unifi iptv set-top box at the TV. Currently, I also have my HTPC connected to TV but it uses wifi for Internet connection. So I wondered if I could share the cable for both iptv set-top box and HTPC since wired connection is always better and more reliable than wireless. Adding a switch/hub at TV side will not work because the set-top box requires a dedicated VLAN port on the router that is different from general internet traffic. Since I know that ethernet up to 100Mbps uses only 4 of the 8 wires in CAT-5e, I wondered if I can use the other 4 wires for a separate network connection. I bought 2 RJ-45 splitter to try but realize they were wired parallelly (basically a Y connection for all 8 wires). Therefore I had to break open the splitter and with a little finger dexterity practice to rewire it as below [sorry for the diagram, drawing on tablet also requires significant finger dexterity :-) ].
After some wire cutting and soldering both splitters, I connected them properly at both ends and it really works! Even with heavy traffic from iptv, no error or dropped packets on PC ethernet connection.



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