Cannot get a wired network to work with a arris comcast cable modem

Having a issue getting a wired ethernet network working when I recently switched to Comcast from att uverse. I purchased a Arris Surfboard cable modem and create a wireless network using a airport extreme. The wireless network works just fine. I have it set up DHCP and NAT. The issue now is that all my wired connections are unable to connect to the internet anymore. I have to run all my devices in wireless mode now. I was trying to keep as much clutter as I could off of the wifi network to help keep proper download speeds. The connections are as followed: Arris Surfboard ethernet connection -- network switcher. Network switcher -- airport extreme & wired devices (blue ray, apple tv etc etc). Has anyone come across this issue? Do I need to go right from the Surfboard modem directly to the airport extreme; then airport extreme to my network switchers with my ethernet cords?

Airport Extreme 802.11ac

Posted on Mar 2, 2016 4:39 PM

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3 replies

Mar 2, 2016 4:53 PM in response to wesleyfromtroy

What model number is your SURFboard?


It sounds to me like you don't have any DHCP for the wired connections, which explains why none of that works. Try connecting a computer directly to the switch and watch its Ethernet settings. I'm guessing that either nothing will happen or the computer tries to assign itself an IP address (usually starting with 169.254....). You might need to try modifying your cable modem settings to make it provide DHCP for your wired stuff.

Mar 2, 2016 6:04 PM in response to wesleyfromtroy

The connections are as followed: Arris Surfboard ethernet connection -- network switcher. Network switcher -- airport extreme & wired devices (blue ray, apple tv etc etc)

If you have a simple modem (it will have only one Ethernet port and look something like the example below)

User uploaded file

Then......your network must look like this: Internet > Modem > AirPort Extreme > Switch > Devices and other Switches



If you have a modem/router (which is really a separate modem and separate router in one package.....like the example below)

User uploaded file


Then.....your network can look like this: Internet > Modem / Router > Switches > AirPort Router, etc.


Do I need to go right from the Surfboard modem directly to the airport extreme; then airport extreme to my network switchers with my ethernet cords?

Yes, if you have a simple modem. If you are not sure what type of modem that you have, post back with the model number of your Arris product.

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Cannot get a wired network to work with a arris comcast cable modem

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