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Cascading Routers -- Conflicting IP Errors

I recently installed a new router to an existing network at a local office where I do computer work. This was done mainly to extend the wi-fi to two outdoor trailers (the building's aluminum walls knock down the "main" office's existing wi-fi signal). They already had a range extender in place for the first trailer, but needed the wi-fi to reach the second trailer. However the issue that occurred involved only the LAN connections on each PC, with the wireless connections disabled on all PCs with wireless NIC cards.

Here's the setup:

1. A modem somewhere outdoors, on a tower (it's that kind of ISP). Make and model unknown. I didn't bother climbing the tower to check. From there, a CAT-5 cable goes to...

2. The WAN port in Router 1 (the original router), which is a Netgear WNDR3300. IP address: 192.168.1.1. DHCP enabled and set to assign address range 192.168.1.100 - 192.168.1.199. Connected to port 1 is a CAT-5 cable that goes to a 24-port Netgear switch. All of the office PC's are connected to this and configured to "Obtain IP address and DNS server automatically". Connected to port 2 is a CAT-5 cable that goes to...

3. Port 1 (not the WAN) in Router 2 (the new router), which is a Belkin F9K1002. IP address: 192.168.1.2. DHCP disabled. Connected to port 2 is a CAT-5 cable that goes to...

4. A wi-fi range extender, which is a Linksys WRE54G. IP address: 192.168.1.3.

This setup worked all day on Friday, but Monday morning I received a call from the Office Manager regarding connection issues (involving hard-wired PCs) and some error messages. I went in to investigate and found that nearly every computer was throwing "IP address conflict" errors. My first thought was that maybe, somehow DHCP got enabled on Router 2. This was not the case, DHCP was still disabled. Disconnecting Router 2 from the network instantly solved the "IP address conflict" issue, and reconnecting it instantly caused the issue to start again.

I cannot, for the life of me, figure out what is wrong with the setup that is making that happen. If I left out any necessary information, please do not hesitate to ask.

I also tried connecting Router 2 to an open port on the Netgear 24-port switch, instead of directly to Router 1, but the issue persisted.
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  1. Best answer
    Hi,

    I don't recommend cascading routers but to configure them as access point or throw the old routers in the garbage and get switches instead.

    Especially the linksys (got crazy bugs and problems at motels ) - mixing brand can create some problems too.
    Also, maybe some computers has ip addresses put in them manually, I would check into that. Do you know what ip address had the problem ?

    Go to the computer with the error message and go to network connection and look at the ip address / or use ipconfig
  2. dextermat said:
    Hi,

    I don't recommend cascading routers but to configure them as access point or throw the old routers in the garbage and get switches instead.

    Especially the linksys (got crazy bugs and problems at motels ) - mixing brand can create some problems too.
    Also, maybe some computers has ip addresses put in them manually, I would check into that. Do you know what ip address had the problem ?

    Go to the computer with the error message and go to network connection and look at the ip address / or use ipconfig



    I'm not at the office at the moment but I know that none of the computers are configured with static IP's. Can't replace the routers with ethernet switches because wi-fi is a necessity, so I think the best option would be configuring as an access point. I totally brainfarted when I was setting the network up, thinking for some reason that if set up as an AP, then it would have to be within range of Router 1's Wi-Fi signal.

    I will try that when I go in on Friday, hopefully that works. So correct me if I am wrong, but I do believe that, in theory, there's nothing wrong with my current configuration, it's just that in practice, certain routers are just a bit finicky I guess?
  3. When you configured your linksys range extender what did you set the default gateway too?
  4. bquick said:
    When you configured your linksys range extender what did you set the default gateway too?


    192.168.1.1
  5. dextermat said:
    Hi,

    I don't recommend cascading routers but to configure them as access point or throw the old routers in the garbage and get switches instead.

    Especially the linksys (got crazy bugs and problems at motels ) - mixing brand can create some problems too.
    Also, maybe some computers has ip addresses put in them manually, I would check into that. Do you know what ip address had the problem ?

    Go to the computer with the error message and go to network connection and look at the ip address / or use ipconfig



    That fixed it: Router configuration page --> Set up as an access point, as opposed to "manually" configuring it that way by disabling DHCP.
  6. pezmutwal said:
    I recently installed a new router to an existing network at a local office where I do computer work. This was done mainly to extend the wi-fi to two outdoor trailers (the building's aluminum walls knock down the "main" office's existing wi-fi signal). They already had a range extender in place for the first trailer, but needed the wi-fi to reach the second trailer. However the issue that occurred involved only the LAN connections on each PC, with the wireless connections disabled on all PCs with wireless NIC cards.

    Here's the setup:

    1. A modem somewhere outdoors, on a tower (it's that kind of ISP). Make and model unknown. I didn't bother climbing the tower to check. From there, a CAT-5 cable goes to...

    2. The WAN port in Router 1 (the original router), which is a Netgear WNDR3300. IP address: 192.168.1.1. DHCP enabled and set to assign address range 192.168.1.100 - 192.168.1.199. Connected to port 1 is a CAT-5 cable that goes to a 24-port Netgear switch. All of the office PC's are connected to this and configured to "Obtain IP address and DNS server automatically". Connected to port 2 is a CAT-5 cable that goes to...

    3. Port 1 (not the WAN) in Router 2 (the new router), which is a Belkin F9K1002. IP address: 192.168.1.2. DHCP disabled. Connected to port 2 is a CAT-5 cable that goes to...

    4. A wi-fi range extender, which is a Linksys WRE54G. IP address: 192.168.1.3.

    This setup worked all day on Friday, but Monday morning I received a call from the Office Manager regarding connection issues (involving hard-wired PCs) and some error messages. I went in to investigate and found that nearly every computer was throwing "IP address conflict" errors. My first thought was that maybe, somehow DHCP got enabled on Router 2. This was not the case, DHCP was still disabled. Disconnecting Router 2 from the network instantly solved the "IP address conflict" issue, and reconnecting it instantly caused the issue to start again.

    I cannot, for the life of me, figure out what is wrong with the setup that is making that happen. If I left out any necessary information, please do not hesitate to ask.

    I also tried connecting Router 2 to an open port on the Netgear 24-port switch, instead of directly to Router 1, but the issue persisted.


    This wouldn't be out at KSC (Kennedy Space Center)would it? Dealing with a certain contractor involved in metal restoration would it? The reason I ask is it's sounding like the manager who loves to fix stuff that ain't broke and blame you....That was me and I was tired of hearing how I was overbilling them yet had to spend my time and effort fixing their cluster &$$& everytime the MGR decided to try his hand at networking instead of STRUCTURAL ENGINEERING!
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