Connecting Motorola SB6121 Cable Modem and AirPort Extreme

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.

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.

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?

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.

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?

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.

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 work...am 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 🙂

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 ...

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.

...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...

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...

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)??

Thanks

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.

THANK YOU!

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???

Thanks for the reply, I think that logically, if you want to share the IP provided by your ISP to multiple PC/Mac at your place you should have DHCP and NAT setup.

Finally, I have redone the installation from scratch and the Airport wizard finally is now setup correctly and the network works as a charm. The key point that solved all this is to switch off and disconnect the Cable modem for at least 5 minutes while your Airport Extreme is the setup mode.

Here is what worked for me:

0. Before doing anything, there was a firmware update for the Airport Extreme, so I did it

1. Unplug Airport Extreme from anything

2. Reset the Airport Extreme to factory default

3. Connect the Airport Extreme to MacBook Pro with lan cable, not in the Wan port

4. Start the Airport Wizard from Airport Utility

5. At the stage where it asks for a Modem/router, switch off the Cable modem for 5 minutes

6. While the Cable modem is off, connect it to the Wan port of the Airport Extreme

7. After 5 minutes, switch on the Cable modem

8. The Airport Extreme wizard will detect the Cable modem and "magically" configure the Airport with DHCP and NAT without my intervention. My network is now in 10.0.1.xxx, managed by the Airport Extreme, all network is then routed to the Cable modem, hiding this part to the internal network.

Key point here compared with other instructions in this thread. I did not reset the Cable modem, just switched it off. It is maintained by the ISP and I did not want to screw up the config.

Another key point, I did the latest firware update (7.6.2 I think) of the Airport Extreme prior these steps and I found out that the wizard has changed a lot. That may explain the "magical" auto setup behavior.

I hope this may help some of you struggling with this.

ocim