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Yodabeesh Level 1 Level 1 (0 points)

I moved into a new house a couple of days ago so of course the first thing that I needed to do was get the home wireless up and running. My ISP is through Comcast. I purchased my own cable modem (Motorola SB6121) instead of renting and used my own AirPort Extreme as the wireless router.


First, if you're purchasing your own cable modem, you will need to contact your ISP and provide them with the HFC MAC ID on the cable modem. Once you've gone through the motions, you will be able to connect your Mac (in my case Macbook) directly to the modem via ethernet cable and access the internet.



When I connected the SB6121 to the AE, I could connect wirelessly to the AE, but I did not have access to the internet. So, basically the SB6121 and the AE were not talking to each other despite being physically connected via ethernet cable.



After days of searching for online answers and forums (and trying different solutions) I was able to successfully get everything up and running. Make sure that you have 2 ethernet cables available.


Here are the steps.


  1. I restored my AE to factory settings just to keep everything simple. Here are instructions: Once you've restored your AE, make sure that both the AE and the cable modem are unplugged from their power sources.
  2. Plug in the power to the SB6121.
  3. Connect your SB6121 directly to your laptop via Ethernet cable. Test to ensure that you have internet accessibility by going to any website.
  4. Remove the ethernet cable from your laptop and plug it into the "internet in" jack in the back of the AE.
  5. Power up the AE.
  6. Connect your laptop to the back of the AE using ethernet cable #2.
  7. Launch a browser. You should now be able to successfully connect to any website.
  8. Assuming that you reset your AE to factory settings, it should just be broadcasting the generic "Airport Extreme" SSID. Disconnect the ethernet cable and connect using wireless to the SSID. Launch a browser and you should be able to connect to the internet.
  9. You can now use the AirPort Utility to configure the AirPort settings.


I assume that this solution would work with any of the base stations.

AirPort Extreme (4th Gen)
  • emh14 Level 1 Level 1 (0 points)

    Thank you so much for posting this. I had the exact same problem and this resolved it.


    The only hangup I had was on step seven.


    I had to unplug the power from the SB6121 for 10 seconds.


    Everything worked after that.

  • StinkoMan Level 1 Level 1 (0 points)

    Thank you.


    My notes on this experience:


    *I didn't reset my Airport Extreme, because it's a Time Capsule and I didn't want to go through the resync with Time Machine.  Also cause I'm a little lazy.


    *I had to reset my modem as did emh14


    Beyond that I can't thank you enough Yodabeesh (awesome name).  You brought the interwebs back into my home.

  • scottrice98 Level 1 Level 1 (0 points)

    This worked well for me up to step 7.  That's where I am stuck at the moment.  I can now get the connection through ethernet to my computer.  However, the Airport Extreme is still blinking yellow.  When I check it in the AirPort settings, it shows 2 errors - "Internet Connection" and "No DNS Servers." 


    As I said, it definitely solved the issue of putting the Airport Extreme between the cable modem (SB6121 like above) and the main computer, but I still cannot get wireless to work.  Any ideas? 

  • jeffinaurora Level 1 Level 1 (0 points)

    I was having the exact same issue tonight.  Just purchased the AE Model A1408 and haven't been able to maintain an internet connection on my iMac whenever I tried hooking it up via the Airport Utility application.  So after I had the SB6121 connected to the AE and the AE connected to my PC with no luck, I then went to the Network icon in System Preferences.  Clicked on "Assist me...".  Then clicked on "Diagnostics..." and followed the directions which basically had me first power down the SB6121 modem and power it back up.  Then I powered down the AE router and powered it back up.  At that point I was now getting an internet connection.  I then took my ipad 2 and went to the Wi-Fi settings and noticed it was asking me to setup a network through my AE.  I selected that and went through the simple steps to set up the network and password and now it all works.  I am a novice so don't ask me why but I now get a green solid light on my AE.  I can connect other devices wirelessly. I can still access the internet on my iMac.  For whatever reason, using the Airport Utility on the iMac doesn't work in my case and using my ipad to set up the wireless network did the job.

  • RussianKnight Level 1 Level 1 (0 points)

    Scottrice98, I'm having the exact same issue as you described. If I connect the Time Capsule to the Model (SB6121) as described by Yodabeesh, I can get internet to work but only wired... the wireless doesn't work and gives the same two errors you mentioned - 'Internet Connection' and 'No DNS Servers'. If I now Power cycle the Modem and the TC, then the Wi-Fi network is established (TC light also turns steady green), but I lose all internet connectivity and the TC status shows no Internet connection.

    Were you able to solve your issue?

  • scottrice98 Level 1 Level 1 (0 points)

    I actually was not able to solve the problem.  I tried every solution that I could find anywhere, including the one here.  I eventually had to abandon the AirPort Extreme and bought a D-Link Router.  It worked immediately with no set-up problems at all.  Hate to say I had to abandon an Apple device, and I hated to spend the extra money, but I wanted it to work and went with the solution that I would work now.

  • RussianKnight Level 1 Level 1 (0 points)

    Thanks for your response... and really... it's sad to hear you had to do that... Now i'm just hoping there's something different about a Time Capsule which would allow it to also interested in trying out the solution mentioned by jeffinaurora... although I don't have my hopes too high ... but have asked for a friend to lend his iPad so i can try it out... just in case it works.... magically

  • RussianKnight Level 1 Level 1 (0 points)

    jeffinaurora, I read through your post and have the exact same issue with a Time Capsule (3GB) ... I just wanted to be sure what you meant when you said you were able to get an internet connection after power cycling your AE. I'm guessing it was only a wired connection and that your Wi-Fi still had issues.... which you subsequently were able to resolve using your iPad to set up the network... am I right?!?!? ...

    Let me know if the solution is still working or if there was anything special you did while setting up the wireless network through the iPad ... i'm gonna try it today evening ...

  • jeffinaurora Level 1 Level 1 (0 points)

    Yes, the AE is wired downstream of my SB6121.  I was able to get the Wi-Fi working via the Ipad.  I haven't had any issues since and the Wi-Fi works just fine.

  • RussianKnight Level 1 Level 1 (0 points)

    ...and here's my entry to Ripley's Believe it or not!!! .... Yes.... it worked!!!... just used my friend's iPad to configure the TC and everything worked as expected...

    I had next to zero hopes of it working... since it somehow didn't make logical sense to me that the TC would work if configured through the iPad, but not if configured through Airport Utility on the Mac... but it worked...

    I'm just a little curious and worried if things will break again if I try to configure the TC additionally now using my Mac (setting up backup, guest wi-fi, etc.) ... but for now, am enjoying the awesome reliability of the SB6121... maybe when I feel up to it... and have an iPad as backup just in case...

  • RussianKnight Level 1 Level 1 (0 points)

    scottrice98, I was able to get it working with an iPad ... thought I'd let you know just in case you still wanted to explore the AE option ... or know someone else who's considering the combination or struggling with this issue...

  • ocim Level 1 Level 1 (0 points)

    I am having the exact same issues and I just want to understand one point on the AE configuration that is now working. In the airport utility on the iPad for "Router Mode" do you set the AE with DHCP and NAT, DHCP or Off (Bridge Mode)??



  • kingkongks Level 1 Level 1 (0 points)

    I had the exact problem with a 2008 Time Capsule, SB6121 and Comcast Internet. Had to unplug my modem at step 7 just as emh14 and StinkoMan.


    Works perfectly.



  • RussianKnight Level 1 Level 1 (0 points)

    ocim, I don't quite recollect this... but I think it was one of the two extremes...DCHP and NAT or Bridge Mode...  maybe you could try with DHCP and NAT and if it doesn't work, then explore if Bridge Mode works???

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