R7300 won't connect to internet through Arris modem

[tomesco]

Hi, hoping someone can help:

I have the R7300 connected via ethernet to an Arris modem (Cox cable) and am unable to establish an internet connection. i have tried cloning the mac address from a previous router and from a macbook pro, i have rebooted both the modem and routers more times than i want to admit. I can see a white solid light on the 7300 which should mean internet, but the genie just can't detect it. I have been able to get directly into the netgear configuration page and have tried to clone a previous router's setup, but just can't get anything to work. It's possible the firmware is way out of date, but a) that probably shouldn't be the issue and b) i don't know how to update it without connecting the router to the internet. any suggestions would be welcome.

[michaelkenward]

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@tomesco wrote:

I have the R7300 connected via ethernet to an Arris modem (Cox cable) and am unable to establish an internet connection.

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What is that Arris modem? Model number?

What happens when you try to connect? What do the LEDs on the R7300 indicate? What firmware is it running on?

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b) i don't know how to update it without connecting the router to the internet. any suggestions would be welcome.

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How do I manually upgrade firmware to my NETGEAR router? | Answer | NETGEAR Support

You can do this by downloading the firmware and then connecting to the router off-line.

[tomesco]

Thanks for the response:

It's an Arris CM8200. I was able to download and update the firmware on the R7300 to V1.0.0.74_1.0.29

The left light is white, and the 3rd and 4th LED are white or blinking indicating traffic. The second LED is usually amber, however, if I use the genie and spoof the MAC address of another router, the LED will go white and blink white, but I still don't have internet access. Interestingly, if I plug the ethernet from the modem into a LAN port (1) on the router, I can then access the router settings using 192.168.1.1 From there, it looks like it's not getting an IP or subnet from the modem. I've plugged in a router that works then tried hard coding the values into the R7300 and still it doesn't connect. When I go back to the WAN port, I can't connect at all to the R7300 other than to see the genie that pops up.

Let me know if any of that helps!

[plemans]

The CM8200 has 2x ethernet ports. But the vast majority of ISP's only allow 1 device to be connected to it. 

If you had more than 1 device, follow this guide. 

Disconnect everything from the modem and the router. (even coax from the modem).

Power both devices off and wait a couple minutes. 

Connect the coax back to the modem and power it on. Wait 2 minutes. 

Connect the router to port 1 on the modem and the wan port on the router.

power the router on and wait 2 minutes. 

Then attempt to connect to the router and go through setup on it. 

Make sure nothing else is connected to the cm8200. 

[tomesco]

Thanks, I did all of that and was able to get into the browser config tool while having the ethernet plugged into the WAN port on the router. I get an IP and subnet etc and all the lights are white, but I still can't get to the internet. I called Cox and they were having issues sending commands to the modem, so at this point I think the real issue is with either Cox or with the Arris Modem. I appreciate the help, if they can't resolve it, i'll post again.

[plemans]

Start with removing any amplifiers, signal attenuators, or splitters from the coax line.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
If you can, simply connect the modem right where the coax comes into the home. This prevents wiring in the home from being the issue. And some ISP’s charge if the wiring issue is in the home. So this helps prevent this.