First of all I have to be clear, I am not interested in solutions including wireless (wifi) technology.

My modem-router (old fashioned - discontinued- wireless) is located on first floor and connects to 2 laptops to the internet. The first laptop is near the modem (but not near enough to plug in my "usbA to usbB" cable). I have it connected using cat5 ethernet cable. The other laptop is going be located 12m away from the modem (cable travelling through furniture, stairs and rooms).

There is not other ethernet port left on the second laptop (the modem has only one, plus an usbB port).

I thought of buying 15m usbA to usbB cable (with repeaters on) to do my job but that is expensive, troublesome and time consuming. The reason I am asking your opinion is that I already have installed a telephone cable between the 2 locations and I own a second modem-router. So, is there any way to use that telephone line to connect my 2 modems and my 2nd laptop in some way so to have access on internet?

One last thing: the modem (DSL line) is connected to telephone jack via cat5 cable, passing through a small adapter device (DSL splitter I think). I also own rj45 to rj11 adapters and rj11 to rj11 connector and a "DSL and telephone line" splitter I think. If I buy 15m cat5 cable and use a hub/switch is possible but troublesome solution, so it is excluded.

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  • 4
    The right way to do this is to install a cheap small Ethernet switch next to your modem/router, and connect both PCs to that switch. Why are you excluding that as a possibility? – Spiff Jan 22 '17 at 18:28
  • Why not just upgrade to a newer router? – Daniel B Jan 23 '17 at 7:49
  • Just to note - this isn't a traditional forum, and answers arn't the space to add to your question. – Journeyman Geek Jan 25 '17 at 3:39

No, there is no way to connect two (customer-side) DSL modems over a telephone line. The reason is that in DSL, the ISP's modem that's on the other end of your phone line (which is part of the DSLAM) is different from the modem you get as a customer: They use different frequencies for upstream and downstream, only the upstream modem sends pilot tones, etc.

The correct way to connect computers that are 12m apart is to use Ethernet. Trying to use USB for that in any way will be expensive, and won't work well.

In a pinch, you can also use an internal phone cable as an Ethernet connection (that has been done successfully over short distances with 100 MBit), but you will need tools to crimp connectors, and knowledge how to do it. So it may be cheaper to just get a new 12m Ethernet cable, and install it.

If you don't have enough Ethernet ports available, you must use some kind of hardware that provides more ports. That can be a cheap internet switch (you can get them starting from 5 EUR, if you look around a bit), or if your old modem-router has several Ethernet ports, you can usually use it as a switch, too (depends on the brand).

  • DSL is not asymmetric. ADSL is asymmetric. "A" in "ADSL" stands for "Asymmetric". We have SDSL which is symmetric. The true reason that they cannot connect is that a DSL router is made so that it communicates with DSLAM. Because your answer is otherwise correct, I am not downvoting it. So, please edit your answer. – user477799 Jan 23 '17 at 7:43
  • @FleetCommand: It's asymmetric in the sense "upstream and downstream do different things", not assymetric in the sense "data rates upstream and downstream are different" (ADSL vs. SDSL). And the first kind of asymmetry applies to all DSL types. Read the spec if you don't believe me. So even if you could reprogram your home DSL router to "not connect to DSLAM", you'd still have to add the training etc. phases. – dirkt Jan 23 '17 at 9:08

There are several way to solve this.

  • If your modem is not just a modem but also has firewall, DHCP and NAT abilities then you can just buy a very cheap Ethenret switch. Connect one port of that to the "LAN" connection on your modem and you are good to go.
  • Alternatively you can buy what most shops sell as a router. This usually is not a router but a combination of router, switch, firewall, DHCP server, DNS server, often wireless accesspoint and sometimes with a modem thown in. You do not need to use all of this functionality. As long as it has the switch part you can do the same thing as with the first answer. It will give you extra options though, and you may have an old modem lying around, in which case it does not matter if it is old. The switch part should be good and other options (such as wireless) are easily turned off. Recap, If you have a spare router then using that as a switch will do the same.
  • Lastly you could add a proper server. Connect that to the modem and use other Ethernet ports to connect internally. This is the most powerful and allows things like home fileserver, but also the most expensive. I susoect that this is not what you are looking for.

That leaves the cables:

USB: Max USB lenght is 5 meters. Buying three 5m cables and repaeaters is not going to be cheap.

Regular wired networking:
RJ11 (telephone cable) vs proper Ethernet cable.
Ethernet cables are wired in a very specific way. The best solution is to buy you 12m Ethernet cable and a cheap switch. You can try to use telephone cable but: 1) This only has 4 wires. 1mbit and 100mbit Ethernet use 4 wires. Gigabit Ethernet uses 8 wires. So Gbit speeds are not possible. 2) You will need to make your own plugs (not to hard if you have the right tools. If you do not have them then you will need to borrow them or buy them. And the tool is more expensive that 12m Ethernet bought in a shop. 3) Phone cable is likely of a lower quality. You might get more errors. It probably is good enough if you force your network card down to 10Mbit and do not use to long cables.

  • @AlexTsakiridis If this answer helped you, you should click accept. – Burgi Feb 8 '17 at 9:16

Simple answer is you shouldn't. While there was once networking done over phone lines, and there's a 'category' of cables that supported it - cat 3 or VG, its unlikely to work well. PURPOSE MADE OEM cables barely hit basic ethernet speeds. Your jerryrigged cables, may not.

Even where cables are specifically designed for data - 4 stranded cable does not work well. If you had a crimper and the necessary connectorsand the existing cable was of an appropriate gauge you could probably attempt it, but its likely to be somewhat fragile. Phone cables are a lot thinner than a ethernet cable for one thing, so you're likely to see a lot of breakage potential.

If you wanted to proceed with this madness...

You'd wire pins 1 and 2 with one pair, 3 and 6 for the other. Unless it was a crossover cable you needed. It'll run at 10mbps at best (and probably be worse, since you don't know the quality of the cable.

And most professionals wouldn't do their own cabling for a short run like that, or even custom crimp cables - they'd buy a good, well made cable and lay it themselves.

What you're trying to do is a sure path to frustration. Especially taking into account the tools and time needed, its probably not worth it.

  • Sorry. My bad, I posted to answers. I am definitely buying ethernet cable and switch. That's a given. – Alex Tsakiridis Jan 28 '17 at 17:03
  • You could/should consider upvoting helpful answers, and selecting the best answer as the correct one. – Journeyman Geek Jan 28 '17 at 22:52

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