Airport Extreme with Motorola sbv5121e

Hello,
I am trying to replace a netgear wgr614 router with an airport extreme. The airport extreme is connected to a Motorola sbv5121e cable modem as it previously was the netgear wireless router.

The problem is that I am not able to connect to internet using the option 'share an address', only in bridge mode. When I try to connect using the share address, the airport extreme is not able to get an address from the router DHCP.
I tried to set up manually the network to the values that I get in bridge mode but using the share mode and it doesn't work.
I have upgraded to the last firmware 7.4.1 and the last airport utility 5.4.1

Any idea?

I have never worked with an Airport Extreme and use DSL here instead of cable.

With DSL modems that have built in routers, the best way to get it to work with a better external router like the Airport Extreme or whatever is to set the modem to Bridged Mode. I am using my DSL modem with built in router with my Linksys WRT54GL and have the Motorola modem in bridged mode and it works great. The Linksys in my case does the DHCP.

Is that Motorola sbv5121e the one that does VOIP? I am downloading the manual to try and help you.

the sbv5121e does not seem to have a router. Where are you selecting Bridged mode? In the Airport Extreme?

The manual for the Airport Extreme is very sketchy so I am just taking a guess here. Did you set the Internet Connection Type correctly? With DSL you usually select PPPoE or PPPoA, but with most Cable systems I have set up, the setting was DHCP.

Hi, the modem is the one with voice capabilities.
I tried to change the configuration of the modem but it is very limited there is only the possiblity to enable/dissable the DHCP (and the frequency for the cable connection).
The airport is set up in bridge mode and with DHCP.
I tried all the other possible configurations and they didn't work.

What happens if you disable DHCP in the Motorola modem and enable it on the Airport and turn off Bridged mode? Did you try that configuration?

When I disable the DHCP in the modem, not even the bridge mode works.
I have read somewhere that this modem is incompatible with the Airpot Extreme, in fact my problem is a general problem of people trying to use it with Unity Media, the German internet provider that I use but I have not been able to talk to them yet.

I guess that Motorola modem is for over there in Germany and Holland. I have found many sites with people having issues but they are all in german and even translated by Google they are hard to understand. I will get back to you if I find more info!

Thanks, I have the same problem (I live in Germany but I don't speak German).

I have raised a call to Apple Germany two days ago. If they solve the problem
(or I find out a way to make it work) I will post the result.

I have found a work around on my own.

1) The Bridge set-up of the AIE works to access internet so set the AIE that way and your mac to get the IP address via DHCP.
2) Write down the IP address and the router address from your network configuration (not the ones from Aitport utility but the ones from the network preferences of your mac).
3) Now set the AIE to work sharing a public IP address and set up the DHCP and NAT as you wish. When you activate this in the AIE you loose the external access in your mac but you have a local network.
4) Set the IP of the network in your mac (not in the AIE preferences) to be manual and put the values that you got from step 2. Now you have again access to the Internet and you have a local network but your mac doesn't see it.
5) Here is the trick to have both. In the network preferences of your mac (not the AIE one) click on the + sign to add an interface, select the interface you are using (in my case the Airport one) and give it a name. Now you have another interface (which should be connected), this is a virtual interface. Set up this interface to be configured via DHCP.

Now everything should work. Of course the rest of the devices in the network don't see the internet but at least your mac can access both, the internet and the local network.