Airport Extreme + CenturyLink + AT&T Microcell = Not Happy

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Airport Extreme + CenturyLink + AT&T Microcell = Not Happy

I am running a brand new airport extreme, in conjunction with a 20+Mbps/2Mbps internet connection with CenturyLink. CenturyLink requires that their Zyxel C1000Z be incorporated into my home network topology. I want the Airport Extreme to take over as much as possible within my home network (carrier authentication, routing, wireless, port mapping, etc). Fortunately, CenturyLink offers a setting within the Zyxel to put their box into a "transparent bridge mode." This works great to accomplish most of what I wanted/needed. However, because of the location of my house, my cell coverage is quite poor. So much so that I am forced to rely on AT&T's MicroCell to improve coverage at my house. Unfortunately, with the Zyxel in transparent bridge mode, it automatically blocks the ports required for AT&T's MicroCell to function correctly. I tried manipulating the port mapping rules within the Airport Extreme to no avail. After testing for open ports, it was almost as if something else was block the ports. So, I gave CenturyLink a call. I was told, by CenturyLink that the only way to be able to manipulate the ports is to remove the transparent bridge mode. I have since tried this, and I have got everything working. In doing so, however, I have had to remove quite a bit of functionality from my Airport Extreme. Basically putting the network in Bridge Mode, and forcing it (the Airport Extreme) to only use its switching and wireless capabilities. Has anyone else run into this situation? Has anyone found a resolution, other than what I have mentioned here?

Airport Extreme-OTHER, Version 7.7.3

Posted on Sep 5, 2015 12:34 PM

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Answer 1

Bob Timmons

Level 10

185,114 points

Sep 5, 2015 1:00 PM in response to Chase R.

I was told, by CenturyLink that the only way to be able to manipulate the ports is to remove the transparent bridge mode.

Correct, this would be true of any modem/router.

In doing so, however, I have had to remove quite a bit of functionality from my Airport Extreme. Basically putting the network in Bridge Mode

Correct, since the CenturyLink modem/router is now handling DHCP and NAT routing services, the proper setting for the AirPort Extreme would be Bridge Mode, which Apple calls "Off (Bridge Mode)".

If you are in the mood to experiment, try setting the AirPort back to a Router Mode of DHCP and NAT. This will produce a Double NAT notice on the AirPort, but you might be able to get away with this on a simple home network. You won't know unless you try.

If things seem to work OK with the Double NAT network notice, Apple does provide you with an option to "ignore" the Double NAT so the AirPort will display a green light.

With Double NAT, you are running a setup that is known as a "router behind another router". I'm not necessarily recommending that you do this....simply pointing out that Apple offers this as an option....and Apple Support will advise you to set up the AirPort this way if you call them. If you want to try this, you will need to make sure that all of your wired and wireless devices connect to the AirPort.

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