Our teacher gave us 4 PC's at school . I want to setup a LAN connection between them all for file sharing via Ethernet cables, and no internet access is available or needed. I have successfully connected the first two with a simple cross-over cable, but I am lost on how to connect all 4. Because I won't use internet, I assumed that I won't need a modem either, am I wrong?

  1. Should I use a modem/router?
  2. How do I? Without internet, that is.


So according to what Paul said, I should just plug in the Ethernet into the hub/router, but all the computers tell me that the cable is not connected, while on the hub I see that it has not detected the computer either.

In short, the devices are only detecting the cables.

Note: Each PC has one NIC


The router is on, but shows no response at all. But I think it is wrong setup. I just connected to power, but someone told me that I need a telephone cable into the wall even if no internet is needed.

  • 1
    All you need is an Ethernet switch (each PC connects to the switch in a star configuration) and assign a unique (private) static IP address (e.g. 192.168.1.x) to each PC. – sawdust Nov 11 '17 at 23:23
  • Are you using crossover cables? – Ron Trunk Nov 18 '17 at 23:11
  • @RonTrunk No I am using straight ones ( I checked the colour pattern test) – TGamer Nov 19 '17 at 0:30
  • So none of the PCs show a link? – Ron Trunk Nov 19 '17 at 1:00
  • @RonTrunk Yes, On each PC in the networking&sharing center I see (LAN2, not connected) and on the router there is really no response at all. – TGamer Nov 19 '17 at 5:05

You won't need a modem but you will need a (cheaper) device called a hub or switch. For your purposes a router is a more sophisticated device than you will need, but it should also work.

Plug a cable from each pc to the hub/switch/router. Usually it would be a straight patch cable, not crossover (aka twisted), but most hubs/switches/routers will auto-sense and work with whatever you plug in.

  • Should also work with a router if that's all you have, answer updated. – Paul Sweeney Nov 11 '17 at 23:35
  • 1
    The answer will give the physical connection. How to get the pcs to talk to each other will depend on what operating system you are using. But provided the pcs do not have wildly different settings, what you did to get sharing working for 2 using a crossover cable should be good for the 4 once they are physically connected. – Paul Sweeney Nov 11 '17 at 23:43
  • But the PC and the hub can't detect the other end. (we found a working ethernet hub) – TGamer Nov 18 '17 at 11:38
  • 1
    The hub won't detect anything, and can't be detected, it's a dumb physical device. You said you had 2 pcs successfully connected using a crossover cable? Plug both those pcs into the hub. They should work exactly the same as before. If not, either the hub or one or both off the cables isn't working. If it's an old hub that can't cope with crossover cables, make sure you are using patch (not crossover) cables. Also check you have lights on the hub and pc sockets when you plug it all together. Report back if that doesn't work, we'll get on to the 3rd and 4th pcs once the first 2 are working. :-D – Paul Sweeney Nov 18 '17 at 11:47
  • I see from your edit that by 'detected' you meant the link light on the socket. In that case confirm correct cables. – Paul Sweeney Nov 18 '17 at 11:54

There are multiple possible answers to this. But let me start with one basic part. If you only have one NIC per computer then you need a device to connect all four to. This is called a switch. Many 'modem' and 'routers' are in fact multiple devices in one box. The four ports on the LAN side usually act the same as a regular cheap switch.

You then have this setup:

                   |  |  |  |
                  /   |  |   \
                 /    |  |    \
       Computer 1     C2 C3    Computer 4

To connect an end device (the computer) to a switch you use a normal ethernet cable.
To connect two similar device (PC direct to another PC, or switch to switch) you would use a crossover cable.

Note that most modern switches include auto MDI/MDX and will auto matically compensate for the wrong cable. As do all gigabit switches.

Lacking a switch or a device which includes a switch you can do something with at least two network cards in each PC, forming a ring. Or one network card per other PC (so 3 NICs per PC in this case). This post shows a nice diagram on on how that was done with 3 PCs. (Ignore the internet part).

I mention that for completeness sake. This is not something you will need in most cases.

That answers the part about the physical connection.

Net up if the configuration. How you do that depends per OS, but assuming TCp/IP you want to give each computer a different IP address. And since you want them to communicate give them an IP in the same network range.

The easiest way for a small setup is to do that manually. E.g.

  • On PC 1 set IP with netmask
  • On PC 2 set IP with netmask
  • On PC 3 set IP with netmask
  • On PC 4 set IP with netmask

That will put all PCs in the network part 10.0.0.x. They can talk to eachother. You are done.

Alternatively you can set up a DHCP server on one of the PCs or on a 'very capable switch' (read: a SOHO router will do) and set all the PCs to DHCP. This means the PCs will ask there network to give them all the needed information. You will have to put the answers to this in the DHCP servers configuration.

The latter is more work and for a simple setup I would skip it. But it scales a lot better and when you get to dozens of PCs this is the way to go.

Lastly, read this post on our sister site serverfault. It explains a lot of the background.

  • Your post is very helpful, but the problem is that none of the PC's can detect the switch. – TGamer Nov 18 '17 at 6:02
  • Even with regular cable? (you mentioned a router which ususally has 100mbit ports. And those need not be MDI/MDX capable. So a crossover cable will fail. Said cable will work when directly connecting PC to PC, but it will not work when connecting PC to router. You can test that by plugging both ends into the router. If the port LEDs light up you have a crosscable). – Hennes Nov 18 '17 at 23:24

You need to use a switch / router. Hub are last centurie's things. Each PC should be connected to the switch with a straight cable.

Then you have to go to network connection and set static IPs for all the 4 PCs in the same network. Check this (bad source, but simple enough concept) to see what's a subnet. You may need to disable Windows firewall too.

BTW: Modern NICs do not need crossed cables to connect two PCs anymore, they negotiate and configure their NIC's ports properly.

  1. Check your lan cards and cables on workability.

    a. Check that your LAN connection actualy works on all PC, connect each one of them between each other(if you have that much time to test 100% connection is ok)

    b. Check your LAN configuration on each PC, so they must be in one network and share same mask example IP: / example MASK:

    no DNS or gateway needed

  2. Then plug all of the LAN cables from PC's to the switch/hub (most modern switches do not care how you cross patch your cables as long as they are the same in configuration)


You can do steps 1 and 2 then put all cables into ROUTER, after that configure router to enable DHCP on it and set all your LAN configuration on PC's to Auto.

If there are still problems and your 1 and 2 steps are ok, see that you OS configuration with network has shared files enabled for local network (Its home network for XP and W7)

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.