Member Avatar for arleneteng

i will begin this by saying that i am not a sys ad, and what i have learned so far was all from tinkering here and there. i really am just a beginner.

i work in a small lab, where our internet connection comes from a LAN cable connected to a main hub. our lab's 9 computers used to be served by 2 switches connected in a series to the main LAN cable. everything was fine until someone gave us a linksys wireless router (WRT54G v5) -- really, we're grateful, but now we can't get 3 of our computers to connect to the network.

what i have are 4 computers connected to the first switch, which is connected to the main LAN cable. the router is connected to the first switch, then is connected via cable to 4 other PCs. 1 laptop is connected via wifi.

so far, i've only gotten one PC to connect via cable connection to the router and the laptop's wifi connection is fine. however, after setting a static IP for that one PC, i noticed that the laptop shares the same IP address (i.e., if i connect to our mail server via telnet from both computers, i look like i'm connecting from the same host). so i need to know, can i change the ip addresses on the computers connected to the router so that they'll be using the department-assigned ip addresses?

also, the other 3 computers connected via cable to the router won't connect to the router (i can't get a ping response from the router using the other computers and none of them will connect to the web-based utility). what did i miss?

i am at my wits end. please help. :sad:

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Brief practical summary for , tied to the replies from , and :

The symptom where multiple lab machines show the same external IP to the department (mail server logs, etc.) is the classic sign that the Linksys is acting as a NAT gateway. If the goal is for each lab PC to hold a department-assigned address and be visible on the main LAN, the device must function as a switch/access point rather than as a routed gateway. The three wired machines that cannot reach the router suggest a port/cable/NIC or subnet mismatch.

Concrete checklist (apply in coordination with the department network admin):

  • Access the router’s admin interface (use the device sticker/manual for the admin address and credentials).
  • Disable the router’s DHCP server.
  • Assign the router a static LAN address that sits inside the department subnet but outside the department DHCP pool.
  • Move the upstream department cable into one of the router’s LAN ports (do not use the WAN/Internet port when operating as an AP).
  • Set the lab PCs to obtain addresses automatically and verify with ipconfig /all (Windows) or ifconfig -a / ip addr (Linux).

Wired-only troubleshooting (addresses and points):

  • Check link/activity LEDs on the router ports. Swap the suspect cables to a known-good port and try a known-good cable.
  • Temporarily connect a problem PC directly to the upstream switch to confirm the NIC and DHCP behavior.
  • If a factory reset is performed, reapply the AP-mode settings and a safe static IP for the router first.

Cautions: changing DHCP or upstream cabling can cause IP conflicts or violate site policy; coordinate with the network administrator. If separation from the main LAN is required, keep NAT enabled and accept that downstream hosts will share the router’s external address.

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Member Avatar for TheNSS

Use the software that came with your router to set it up. You probably want all the computers in your lab to connect to the router. If your router is configured as a DHCP server, then don't give your computers static ip addresses. You can choose for your router not to be a DHCP server then you can assing ip addresses to your computers

Member Avatar for rcpo197

You may need to replace the cables on the computers that cant ping.

Member Avatar for cc11rocks

ahh...i've had this problem many times...reset the router...connect the router to your computer through the ethernet port...type in your adress bar...admin...make settings the way you want to...DO NOT USE THE INSTALLATION CD-ROM OR THIS WILL NOT WORK

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