Can't access internet after changing IP!

Discussion in 'Tomato Firmware' started by agentdiscount, Dec 1, 2008.

  1. agentdiscount

    agentdiscount Addicted to LI Member

    I changed my IP in Tomato's Basic->Network area from to because I was trying to setup port forwarding with my DSL modem. This DSL modem requires that all IP address to receive port-forwarded connections be in the same subnet such that the DSL modem and the destination workstation are in 192.168.0.x.


    However, once I made this change I am unable to access the internet from any computer. I can't even get back into the tomato admin gui on the new IP address since DNS apparently doesn't work anymore.

    My machines are able to use DHCP to get an IP address from the WRT54G and Tomato, but I am unable to do anything else. No ping, no DNS. I can ping other machines on the same switch, but that's it.

    What can I do to restore my connectivity? I don't want to lose all my tomato settings, either!

    Thanks for your help.

  2. ifican

    ifican Network Guru Member

    so from the picture your internal network was 192.168.3.x. When you changed the router ip did you also change the dhcp range? What is the subnet mask you are using and what ip range are you getting from your cable modem?
  3. agentdiscount

    agentdiscount Addicted to LI Member

    My internal network was which I believe is the default value. When I changed the router ip, tomato automatically changed the dhcp range to give addresses in the 192.168.0.x space. I didn't change the subnet mask from the default value, which should be
  4. ifican

    ifican Network Guru Member

    what ip range is being used on the wan side?
  5. agentdiscount

    agentdiscount Addicted to LI Member

    You mean where is the DSL Modem? That should be on If I'm not giving you the right answer, where would I find the IP range on the WAN if I can't even get into either WRT54G or my Actiontec DSL Modem via the Web GUI?
  6. fyellin

    fyellin LI Guru Member

    Did you tell all your computers to get a new DHCP address?

    Any computer that still has an old DHCP address won't try to renew it until you tell it to. They will be unable to access both the internet and the router because they won't know how. (They'll think the router is on a different subnet, and they still have the old address of the router as a gateway).

    You can usually force a computer to renew it's DHCP early by (a) turning off the wireless and then turning it back or (b) pulling the ethernet cable and plugging it back depending on how you're talking to the network.
  7. agentdiscount

    agentdiscount Addicted to LI Member

    Yeah, that's the first thing I did is to force the computer to get a new IP. I ran ipconfig /release and then /renew. After that failed to restore access, I restarted the WRT54G and then -- later -- the DSL Modem.

    I can confirm that I am communicating with the router via DHCP as my IP addresses for my devices are 192.168.0.x now instead of 192.168.1.x as they were before the router IP change.
  8. SgtPepperKSU

    SgtPepperKSU Network Guru Member

    What does ipconfig show for IP Address and Default Gateway?
  9. ifican

    ifican Network Guru Member

    Ok so this is what i think happened and the stem of the questions. It sounds like your wan (internet) side of your tomato router is also 192.168.0.x as well. This will not work as you have discovered. Change you lan (tomato internal) space to anything other than 192.168.0.x and you will be fine. This will fix your connectivity and then we can discuss what you are trying to do.
  10. sunjon

    sunjon Network Guru Member

    Any reason why you're running such an old Tomato build?
  11. agentdiscount

    agentdiscount Addicted to LI Member

    ifican was definitely right. I really appreciate the help from everybody here.

    I must have been using the same IP on the router for both external (WAN) and internal (LAN) networks. In order to even access my firmware GUI, I disconnected the DSL modem and then renewed my DHCP lease so I was able to connect to without the WAN trying to hijack that address. Then, I was able to reset the LAN IP address back to

    So, any suggestions on how to do port forwarding when I have both an access point running tomato and a DSL router behind that that refuses to forward ports outside the WAN IP range (192.168.0.x) to ports inside the LAN (192.168.1.x)?
  12. agentdiscount

    agentdiscount Addicted to LI Member

    Actually, that was a screen shot I swiped off the web just to illustrate my point. I'm currently running 1.20.
  13. mstombs

    mstombs Network Guru Member

    It is clear that tomato is acting as a NAT router, not an access point, and you are running "double NAT". This should work, even portforwarding if you put the router in the DMZ of the modem.

    The best complete solution if your ISP connection is PPPoE is to put the modem in full bridge mode and enter your PPP login details into the router.
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