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I have a DSL modem setup with local IP 192.168.1.1. Everything working fine. I also have a LinkSys wireless router that I have connected to the DSL modem.

I've enabled DHCP on the wireless router, and have assigned 192.168.107.1 address to the router, with 255.255.255.0 as the mask. Now, from the wireless router, I can ping to everywhere, which means the connection between the wireless router and the internet is fine.

However the connection between my machine and the internet doesn't work. I get an IP assigned but nothing else works. Anything I'm missing?

The router is configured to assign IP addresses from 192.168.107.100 onwards.

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migrated from serverfault.com Mar 19 '12 at 15:24

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It sounds like your modem is also a router and has its router features enabled (that's why it has a private IP address). If you want to use the modem as just a modem, you need to set it to bridging mode. How is the modem connected to the router? Did you connect the modem to the router's WAN port? (That's correct if it's a bridge but incorrect if it's a router.) –  David Schwartz Mar 19 '12 at 15:35
    
Did you check the DNS? –  Neel Mehta Mar 19 '12 at 15:36
    
You probably don't have a DSL modem but a router. You should have PPPOE (or PPPOA) assigning a public IP to the external interface of your router. The modem should be bridging traffic from it's rj11 (PSTN) interface to the rj45 (ETHERNET) interface. The router should be configured to masquerade (NAT) all internal traffic with its external interface public ip. –  dAm2K Mar 19 '12 at 15:40
    
Thanks! Yes I did connect to the router's WAN port. I do not have a rj11 at the back of my modem. Just a rj45 interface and a USB port. WHy should I have PPPOE enabled on my router when my modem is handling it anyway? I understand I need to use it as a bridge.. Is the modem serving as a DHCP server a problem? –  Kid_A Mar 19 '12 at 17:05
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1 Answer

Set your DSL modem to BRIDGE mode (PPPOE or PPPOA). Call your dsl provider for connection details. DHCP server on the modem should be disabled.

The DSL router should be physically connected to the modem via an ethernet cable. This cable should be attached to the router's extenal wan interface (it should be marked WAN, DSL, should be of another color, something like that).

The Router should be configured to NAT anything internal to its public interface. You should configure your router to enable DHCP server. It should be configured with dns proxy enabled.

Drop any firewall rule you may have and begin to create the rules from scratch (if you need it).

Try pinging the default gateway (internal router interface) then try pinging a public IP, then ping www.google.com to check if DNS is working.

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Thanks much! If the DHCP server on the model is disabled, how will I connect to the modem if my config doesn't work? –  Kid_A Mar 19 '12 at 17:06
    
@Kid_A you could set a static IP of a subnet that does not overlap, something like 192.168.2.0/24. You could for example set a static IP address on the modem (192.168.2.1 - netmask 255.255.255.0). On the router you have to do nothing. Now from one of your PC behind the router you should be able to open a browser and connecting to 192.168.2.1 you should be able to reach the modem through the router. –  dAm2K Mar 19 '12 at 17:55
    
Didn't work. Couldn't connect to 192.168.2.1 via my router. Had to reset my modem :( –  Kid_A Mar 19 '12 at 19:11
    
It should work. A router in NAT must forward the traffic to any external network. If it failed something gone wrong... –  dAm2K Mar 19 '12 at 21:05
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