router and cablemodem don´t work together

I have a Motorola SBV5120 SURFboard cablemodem and I´ve never experience any problems connecting to Internet. But I tried to use a Tenda W541R router and I can´t access the Internet. My Internet provider support service said there´s no problem with the modem (I still can connect if I use it alone), but I can make the router connect in anyway. I can enter the router settings (using but it doesn´t detect the modem. I have dinamic IP, but seems the router can´t find it.
Do I have to set something in Windows 7 in order to make my router "see" the modem´s connection?


Noob Whisperer
Hello and welcome to the forums. Is it possible that your Internet Service Provider requires a username and password to support what's called PPPoE, if that's the case you will need to embed that information into the router configuration probably somewhere on the WAN interface page.

It's probably in the router. You may have to set it to spoofing. I think that's what I had to do with mine. You can access your router menu through an ip address. Just google your router and find the directions.

Thanks for your responses. I finally managed to make the router connect to the modem, by assigning the connection parameters manually (IP address, DNS, gateway and DHCP).
The problem is that I have a dynamic IP, which changes every 6 or 12 hours. But if I select the "dynamic IP" option in the router configuration, the Internet connection stops working again.
I'd like to know what can I do in order to make the router detect the IP automatically, so I don't have to change it manually everyday.


Noob Whisperer
Not sure exactly where you got the information that you manually assigned to the router inorder to get it working. Usually setting the configuration to "Dynamic" and clicking the release and renew button a couple of time should resolve the issue and normally any router configured as a DHCP client should start DHCP solicitations well before the DHCP lease expires and should be able to renew the lease. So I suspect you need to communicate to your ISP exactly what you are attempting to do and perhaps they can provide some assistance, it seems that perhaps you need to put the modem in bridge mode and then let the router handle the communication with the ISP, I'm sure they would be able to help walk you through this process if indeed that particular modem supports bridging.

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