I currently have internet service with At&t and interested in wiring an Ethernet connection into one of the rooms in the house (I will call this room1). I called At&t to ask how much it would cost to wiring just 1 line of Ethernet and it comes out to be ~&150.00. So I decide to do it myself.

Some background information. The house came pre-wired with Cat5e cables. All of these wires are bundle up in the attic. So, in each room, there is a Cat5e port. All of the jacks in the house are phone jacks, and the other ends in the attic are not terminated yet. Also, none of the ends in the attic is labeled, so I don't know which one ends up in which room.

Currently, the modem is sitting in the living right next to a phone jack. The only thing that it's connected to is the At&t fiber box outside the house.

So here are what I have done so far: 1) I changed out the phone plate and phone jack near the modem. I replaced it with an Ethernet keystone jack using a punch down tool and by following the TIA568B configuration. 2) I plug an Ethernet cable (Cat5e) from one of the Ethernet ports of the modem to the new Ethernet jack. 3) I went to the attic and terminate all of the Cat5e cables with rj45 connectors using TIA568B and a crimping tool. 4) I try to determine which cable is connected to the modem by plugging each of them into my laptop.

So far, none of the cable gives me an Ethernet signal. Before I went to the attic, I plugged an Ethernet from my laptop directly into the modem and was sure that it works. So where have I gone wrong? Why doesn't any of the cable giving me Ethernet signal when I plug it into my laptop?

Also, here is the rest of my plan, once I found which cable is from the living room (i.e., the cable that is plugged into the modem): 5) Connect the living room cable to the cable of room1 using an Ethernet keystone coupler. NOTE: I am aware that most situation would have used a switch to do this step, but since I only need one Ethernet connection (we only use 1 desktop computer in the house), I decide to use the coupler instead. Is this reasoning incorrect? 6) Change the phone jack in room1 to an Ethernet jack. DONE!

So, beside not understanding why I do not find any signal from any cable in the attic, is there anything wrong with the process that I proposed?

Sorry for so may words, this is my first time doing this, so I try to make sure I am not doing something wrong.

  • You might not have the right cable or it’s bad or your crimps are bad. Just no way for us to tell. If it were me, I would wireless router the setup and add WiFi to the desktop computer Commented Mar 31, 2019 at 1:28
  • @UnhandledExcepSean WiFi is often the best solution. But when the wiring isn't too hard it is, in my opinion, well worth it and far superior to WiFi. Commented Mar 31, 2019 at 2:02
  • @manassehkatz I agree that a wired connection is better in most ways, but buying tools for this seems like a waste to me. In my opinion, the OP is better off going to WiFi to solve this issue Commented Mar 31, 2019 at 2:34
  • @UnhandledExcepSean Obviously there is a limit to the effort & expense that is worthwhile in any project. OP already has a punch down tool, so perhaps additional tools would be useful other times. Or not. Hard to guess. I did see "desktop computer" so that rules out "trying to hook up my server rack" where WiFi would not be a practical alternative. Commented Mar 31, 2019 at 2:54
  • @UnhandledExcepSean the desktop currently has a wifi card, but the signal is not very reliable since there are about 3 layers of wall between the desktop and the modem
    – David
    Commented Mar 31, 2019 at 4:37

1 Answer 1


Your basic plan is just fine. The key problem you are having is figuring out which cable is which. The secondary problem you may be having is making sure the jacks are wired correctly. There are tools designed specifically for both of these tasks. Pros get the good stuff. For a once-in-a-while use you can probably make do with the cheaper versions. A couple of specific examples:


That's "generate a tone and detect it", not "powder that goes in a laser printer" :-)

While you can buy a tone generator and a tone detector as separate items, normally you buy them together. Here is one I purchased recently, which I like because it is relatively inexpensive (so I don't get too upset if someone borrows it and breaks it) and it has "ends" for Ethernet, coax, phone, etc. so I can use it for any type of wiring job.

 Sperry Lan WireTracker Tone and Probe Wire Tracer

Cable Tester

There are plenty of these around. When I started in the network business, similar devices cost a few hundred dollars - and were worth every penny. I currently have a Klein Tools VDV LAN Scout Jr. Tester:

Klein Ethernet Tester

which includes one adapter for the remote end and gives very quick readings of the status of all 8 pins. There are plenty of others - e.g., some on Amazon for < $10, though some cheapies will last a long time, some will list a reasonable amount of time (1/5 the cost, 1/5 the lifetime and if you only need it once in a while that works great) and some hardly work at all. YMMV.

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