Member Avatar for berryjuice

Hi. I have a Linksys WRT54GS router and a Motorola SB4100 Cable Modem. I'm trying to set up a network so that all of my computers can connect to the internet.

If I connect the SB4100 modem directly to a single PC, the internet is working fine. But if I will connect the SB4100 modem to the Internet port of the router and after cloning the MAC address of the LAN adapter of my PC to the router, i do not get internet connection at all.

the weird thing is that the router status have all i need to connect to the internet. i get the domain name of my isp, my ip address on the internet (not the 192.168.xxx.xxx), a default gateway and 2 DNSs. they are the same informationi get when i connect directly from modem to PC that runs smoothly. on my computer, i get the usual 192.168.xxx.xxx from the router, the default gateway ip address of the router, etc. it seems that everything is fine.

am i missing something? please suggest all the necessary steps to solve this problem bec. i beginning to explode just figuring this one out. Thank you very much in advance.

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Symptoms show the router has a valid public WAN address while clients receive private 192.168.x IPs but cannot reach the Internet. The most common cause for that exact symptom on Linksys boxes is NAT being disabled (the router acting purely as a router rather than a gateway). Verifying where packets stop will point to NAT or routing/firewall misconfiguration rather than a simple MAC-clone problem.

Quick checks to run from a client machine:

ipconfig /all
ping 192.168.1.1
ping <router-WAN-IP>
ping 8.8.8.8
tracert 8.8.8.8

If the LAN ping to the router succeeds but ping 8.8.8.8 fails while ping <router-WAN-IP> succeeds, the router is not NATing/forwarding.

Practical fixes to try (in order):

  • In the router web GUI go to Administration -> Advanced Routing and set Operating Mode to Gateway (enable NAT). Save and reboot.
  • Ensure Internet Connection Type is Automatic/DHCP (unless the ISP requires PPPoE/static).
  • Power-cycle the cable modem after any MAC or device change so it relearns the attached device.
  • Temporarily disable SPI/Firewall to test. If that helps, re-enable with defaults and selectively adjust.
  • If problems persist, try a factory reset, reflash/update firmware to the latest official release, and retest. Use a different Ethernet cable/port while testing.

correctly flagged UI quirks around MAC cloning; because the router already shows a public WAN IP, cloning is unlikely to be the blocker here though the modem should still be power-cycled after any MAC change. ’s duplicate-MAC concern is possible if two devices were attached simultaneously, but the NAT/gateway setting is the most likely root cause given the reported status.

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Member Avatar for vikonava

I have a linksys router too, and what ive noticed that when cloning the Mac Addres it gives you abutton called CLONE ADDRESS or something like that and SAVE button, and when you click the CLONE ADDRESS button it changes you the Mac Address something like addres encryption way and then you are supposed to click save. Well you should write your mac address and click SAVE button directly as that other button just changes your addres ¬¬ had this problem too in the past

Member Avatar for The Dude

Maybe having 2 of the same Mac address's on @ the same time causes a conflict??

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