LAN via router problem with two PCs

My old PC (XP Pro) was connected to LAN1 on my router, which was connected to my cable modem. No problem.

Built a new computer (also XP Pro), and connected it to LAN2 on my router. With a little work, I was able to map to the C drive on my old computer, so that I could transfer files. So far, so good.

Then, I switched the two computers. Old computer now in LAN2, new computer in LAN1. I reconfigured my router so that the DHCP reservation points to the new computer's IP. Under Dynamic DHCP Clients, I have my old computer's IP. I have powered down both computers, restarted the router and cable modem.

The problem: I can no longer map new PC to old PC. I've made sure that both use the same workgroup name. If I open up Microsoft Windows Network on my new PC, I see... my new PC, along with a shared folder from the new PC. Meanwhile, the old PC can map to a shared folder on the new PC. So, basically, everything is backwards now: instead of mapping new to old, I can only map old to new.

If I try to map to the old PC's IP address, it times out. Can't ping it, either. However, using the router's control panel, I can ping the old computer successfully.

What did I mess up?
14 answers Last reply
More about router problem
  1. Hi good day!

    I might be able to help you with this but I need further information.

    - Model and brand of router.
    - IP address on both pc's.
    - When you re-configure DHCP reservation on the router,were you able to check if tha MAC address falls on the desired IP address?
  2. Why would you need to know the exact IP addresses??
  3. They're private IP addresses so it doesn't matter if you post them. Why are you using reserved IP addresses anyway? Also, all the LAN ports on the router are identical. You're making things way too complicated.

  4. I am not using reserved IP addresses. They were automatically assigned by Comcast, and stay constant unless I disconnect my Comcast cable modem for a long period of time, in which case Comcast can assign a new IP.
  5. Also, the reason I reconfigured the router is that the old computer is going to be disconnected from it once I'm done transferring files.
  6. Good day!

    You're using a router so therefore if comcast will assign an IP, it goes only on the WAN part of the router not on the LAN part.You can't network pc's on LAN using public IP assigned by an ISP.Router's usually assign an IP of 192.168.1.x or 192.168.0.x and they're private IP's.

    Anyway were you able to try connecting them back again as they were setup originally.Does it still work?
  7. That's not correct. Each computer has a unique IP assigned by Comcast, and the IP address is static unless I unplug the modem for a long time.

    If I run the ipconfig command on either machine, I see its IP address (in the form; each PC has a unique number in the last three digits of the IP). And, as I said, the two machines were networked previously.
  8. hmmm...Interesting..your ISP can assign static IP directly to both pc's and it's private IP address coz as far as I know an ISP irregardless if its DHCP or STATIC, it will only assign one IP address to a client and it's public or routable IP that you mentioned are non-routable IP but it works of coursew locally when networking computers. May I know the model and brand of the router?

    Were you able to try connecting them back again as they were setup originally.Does it still work?
  9. The router is a Zyxel x-550.

    The two computers are still connected in the same way -- network cable from one to the other. The only changes were to plug them into different LAN ports, and to reconfigure the router. So I'm really not sure how to change them to the way they were before, without reconfiguring the router again.
  10. Is this how the setup scree of the router looks like?
  11. Not quite... but here's a link to the x-550 manual, which shows all the screens.
  12. I've seen the setup page of your router and there's no LAN port setting where in you can specify an IP address irregardless of what device(e.g. pc,gamin console) is connected to it.

    If you'll check the router status under device information,under WAN information on the IP address,that's the IP provided to you by your ISP.It could be either DHCP or STATIC.However on the LAN information the IP address is the router's IP.

    Now looking on the BASIC settings,if mode is ON DHCP, you'll see there the range of IP address the router can generate for a certain number of pc's.It means that IP address on both pc's are generated and distributed by the router itself and ISP had nothing to do about it.Kindly check the range of IP address.

    Well going back to the issue,there might be a firewall enabled that might be blocking you from maaping the other pc.
  13. Thanks for the help. I'll do some digging.
  14. You're welcome!
Ask a new question

Read More

LAN Routers Computers Networking