Cable modem internet works when directly plugged into desktop, but when run through the router, no connectivity

Most cable Internet Service Providers (ISP) use a Media Access Control (MAC) Authentication to establish Internet connections for end-users. A MAC address is a unique 48-bit (6-byte) integer that is attached to an Ethernet NIC for each computer. To set-up your Linksys router to a Cable ISP, you have to do MAC Cloning. MAC Cloning is a procedure which enables a router to copy the MAC address of the PC that's registered with the ISP.
To setup a Linksys router with Cable connection you need to perform five steps:

1. Verifying Internet Connection
2. Connecting the Devices Together
3. Checking the Router's LEDs
4. Configuring a Linksys Router for a Cable Connection
5. Power Cycling

NOTE: The image may vary depending on the computer and modem you're using.
Once an active Internet connection is established through the modem, connect the modem and the computer to the router by following the instructions below.
Connecting the Devices Together
After ensuring that you have an active Internet connection, connect the modem to the router's Internet port and the computer to any of the four Ethernet ports. For instructions, click here.
After connecting the devices, check the LEDs by following the instructions below.
Checking the Router's LEDs
The Linksys router's front panel will indicate the status of the connection. After connecting the broadband modem to the WAN or Internet port, the computer to an available numbered port and powering on the router check the lights on the front panel of the router. For instructions, click here.
After checking the router's LEDs, configure the router for cable Internet. For instructions, follow the steps below.
Configuring a Linksys Router for a Cable Connection
For Telstra Cable internet users, please contact Telstra to confirm if your internet connection is using DHCP or HB (Heart Beat) signal. There should be no other machine running HB client upon doing this procedure.
Step 1:
Access the router's web-based setup page. For instructions, click here.


NOTE: If you are using Mac to access the router's web-based setup page, click here. If you forgot your IP address, click here. If you forgot your router's password, click here.


Step 2:
When the router's web-based setup page appears, click the drop-down arrow under the Internet Connection Type field and select Automatic Configuration - DHCP.
(a) If you are NOT using Telstra HB, proceed with DHCPcable modem internet works when - kb4682-003_en.png>
NOTE: If you are a Telstra Cable internet user and you're using WRT120N, WRT160N v1, WRT320N or WRT610N, please select Telstra Cable.
(b) If you are using Telstra Cable, proceed with the following setup. Obtain your user name and password from Telstra. Please disable any HB client that might have been previously running cable modem internet works when - kb4682-004_en.pnghe router is configured.

Step 3:
Click .

Step 4:
Click MAC Address Clone.

Step 5:
Select Enabled and click Clone My PC's MACcable modem internet works when - kb4682-012_en.pngbr />

Step 6:

Click .


Step 7:
Click Status. Check the value of the Internet IP Address. If the Internet IP Address has numbers, this means the router has been properly configured. You should now be able to access the Internet. If you're not online, perform a power cycle to synchronize the router with the modem. For cable modem internet works when - kb3687-005_en.pngick here.

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NOTE: If the Internet IP Address is all zeroes (0.0.0.0) click first then click . If the Internet IP Address is still all zeroes (0.0.0.0) perform a power cycle. For instructions, click here.
If the IP Address starts with 192.168.1.xxx or if it has the same first three numbers (octets) as the router's IP address, change the router's LAN IP address to a different LAN segment. For instructions, click here.
Once the router is configured, perform a power cycle. For instructions, follow the steps below.
Power Cycling

Step 1:
Shutdown the computer.

Step 2:
Unplug the router's power cable.


Step 3:
Unplug the Broadband modem's power cable and wait for 30 seconds.


Step 4:
Plug in the Broadband modem's power cable and wait for its lights to appear stable.


Step 5:
Plug in the router's power cable once the modem's lights appear stable.


Step 6:
Power on the computer on and test the Internet connection.
NOTE: If you're not online after performing this procedure, you may need to upgrade the firmware of the router.