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Lpens's avatar
New Contributor
4 years ago

2 Ethernet Ports on Modem

Has anyone been able to get both ethernet ports on their modem to work at the same time?

I have an Arris SB8200 (that has 2 ethernet ports on the back) and I would like to have one ethernet cable plugged directly into my computer, and another running to my router.
When i do this though, I get internet to the computer OR the router, but not both at the same time.

Arris customer support says the modem will run both ports at the same time if the ISP (Cox) will provide me a second IP address which I am willing to pay for, but every Cox "tech" that I have spoken to on the phone either doesn't know how to do this or doesn't think that Cox can issue another IP address to the same modem. 


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  • Bruce's avatar
    Honored Contributor III

    When delving into topology, stop using the word "Ethernet."

    A modem has a WAN port...not a LAN port.  At best...if it's active...the 2nd port won't have Internet service but your other devices may be able to discover the 2nd port via layer-2.

    • Lpens's avatar
      New Contributor

      Arris calls them "ethernet" ports on their own model info...

      Thanks for the sort of helpful response

      • Bruce's avatar
        Honored Contributor III

        On the device itself, yes, it's an Ethernet port to accommodate an Ethernet cable.  However, you're networking devices and Ethernet is a vague term.

        A modem has a WAN port, router LAN ports and Mouth is correct about LAG.  Some call it a switched port.

        I don't believe you need a second IP address.  Perhaps a switch off the WAN port and then a router and computer off the switch.  Cheaper than subscribing to a second IP address.

  • bearone2's avatar
    Contributor III

    i use both ports with my 4141 panoramic unit, hardwired to pc, 2nd port to old netgear router to run 2 older dell laptops.

    both function at the same time.

    • Becky's avatar
      Hi Lpens, only one gigabit Ethernet port on the Arris SB8200 is active at a time. -Becky, Cox Support Forums Moderator