Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am having problems connecting a machine that has previously worked on my network. Here's what has happened;

  • I have three PC's
  • Two of them are older and run Windows XP Pro and one is the new PC running Win7 Pro
  • Machine A (Windows XP Pro) has been my "server" with all my files
  • Machine B (Windows XP Pro) has been my "workhorse" design machine
  • Machine C (Windows 7 Pro) is the new "workhorse" design machine
  • All three machines have been on the network so that I can copy files from B to C as C is the new machine I will be working on from now on.
  • I then moved my CAT5 cable to the second story of my house where the "server" (Machine A) would go from now on.
  • I know the cable works as I plugged a laptop in and was able to browse other machines from upstairs.
  • If I plug machine A in though, I can see connectivity on the lights but I cannot see this machine on the network.

I then plugged the other machine in (B) and it too was not seen on the network. I left it over the weekend and miraculously, it showed this morning.

Of course, I don't need B to be on the network but A as it is my file server but again, it is not online.

I am wondering if it is an IP address issue and how can I remotely release an IP address of a machine or is there a way of releasing an IP address on a specific port (plug) of the router?

share|improve this question
You kind of forgot to describe the problem. What does "was not seen on the network" mean? Did it have an IP address assigned? Could it reach the router? Could other machines ping it? – David Schwartz Jul 30 '12 at 10:16
The easiest way to 'release' it (if I understand correctly) from the memory of the router is to restart the router - this means when it connects, the router will resend the IP's via DHCP etc. Is this what you meant? – Dave Jul 30 '12 at 10:21
Thanks guys, I will try your suggestions of restarting the router now in the hope that it releases the IP addresses and assigns new ones. David S, I cannot see the PC on the network through regular Windows Explorer. I also use FING on my Android phone and normally, it will show me what PCs/Devices are on the network. – SixfootJames Jul 30 '12 at 12:33
up vote 0 down vote accepted

Look at your router. I assume you use a router. You never said! Cause it could be that you're on a hub/switch where Machine A was actually assigning all IP's and acting like a DHCP server. You also never said how you're looking at your network although I might assume you're using a file browser. Therefore, you really need to look at your router's details and things like lease times as well as just exactly what's assigning your network IP addresses.

For example, are your own network IP's "dynamically" assigned via DHCP from your own router or are they doled out somewhere else? Typically, IP's come from a router via DHCP but they could instead be assigned from a separate "DHCP server". So could it be that Machine A was doing more than just serving files? Or could it be that you're needlessly paying your ISP for more than one IP address?!!! (I sure hope not. But again, you didn't say.)

You might also want to look at DNS services too. Again, this is typically handled in a typical router where it's all too common to just let your ISP handle it by not assigning any IP for a better DNS service (one like Open DNS - You can always over ride DNS services either at the router level or even via each PC's IPv4 settings. But get it wrong and nothing is likely going to work. And that's assuming you're not running your own DNS server or relying on your own hosts lookup tables or something like that! (I'll also assume you're not using IPv6 since it's still not widely used too.) So assuming there aren't other weirdo considerations like null Ethernet cables or something, it really sounds like you simply need to wait for your router and network.

I think I should also say that there may still be other considerations such as network groups that XP doesn't easily deal with. Sharing files/folders and even file permissions may be other things to worry about. And that's just for starters! But I think you said the 3 PC's can at least share files so I hope I don't need to elaborate. (Not that I would since this is a drive by comment.)

share|improve this answer
Thanks Anon, let me start with the router and see if there is something I can do there. Will get back to you once I have tried everyone's suggestions. – SixfootJames Jul 30 '12 at 12:34
Thanks Anon. I managed with a mix and match of your suggestions – SixfootJames Aug 15 '12 at 14:52

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

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