Guest Network Not Working Airport Extreme

I've got a perfectly reliable DSL Modem/Router with routing turned off, but I can't get a simple thing like a guest network.

If routing (NAT & DHCP) is disabled on your combination modem/router, then you should be able to use your AirPort Extreme in its default router mode in order to have its Guest Networking feature available. Is this not the case?

Seems that this is indeed a limitation of the Extreme ie it won't support Guest in Bridge mode. Wonder why that should be?

Well, in Bridge Mode, the AirPort Extreme can only work with the settings that it recieves from the upstream modem/router....and that device can only provide IP addresses for devices on one network.

Since the Guest feature is another separate network, the modem/router cannot also assign different IP addresses on another range to allow the guest feature to operate correctly.

IF.......the AirPort Extreme were providing IP addresses, devices on the "main" network receive IP addresses in the 10.0.1.x range, while devices on the guest network are issued IP addresses in the 172.16.1.x range. This is done through a process known as VLAN, or Virtual Local Area Network....a feature that the modem/router does not have.

NAT ON and DHCP ON was how I started out, and I think this was how the Extreme configured the modem/router when I first installed it. I don't think I had to go into the modem/router settings, the Extreme handled it on its own (which I thought was cool).

Both the Zoom & the Extreme are, by default, Internet routers. The Zoom, unlike the Extreme as you know, has a built-in ADSL modem.

When performing as a router, both NAT & DHCP are enabled. If they are enabled on the upstream (closest to the Internet) device, the downstream should have both disabled. Otherwise you would find your network complaining that it is in a Double NAT condition.

You already know that the Extreme cannot provide a guest network if both of these services are disabled. That is, when it is in bridge mode. The Extreme cannot reconfigure another router automatically or manually.

The goal to gain access to the guest network was to disable both NAT & DHCP for the Zoom AND enable them both for the Extreme. Not just disable the Zoom's wireless radio. You want the Zoom to be in bridge mode and the Extreme to perform as the router.

If the Guest Network feature is important, the Extreme can be configured to provide DHCP and NAT service as well, but you will wind up with a condition or "error" known as Double NAT when you do this.

Depending on the complexity of your network the "error" can range from a minor problem (which Apple allows you to "ignore" in the settings for the Extreme) to a deal breaker if you are trying to run an online gaming console on the network, or connect from a remote location to control security cameras or access hard drives on the network.

This is the method that Apple Support suggestes when users call and ask about how to set up the Guest Network feature with a modem/router "upstream" on the network.

The upside....it might allow the Guest Network feature to operate.

The downside....Double NAT can produce some unpredictable results on the network.

I'm not recommending that users try the Double NAT setup......just pointing out that it might be a potential workaround if a Guest Network feature is really important to have.

Technically, it is your modem/router that should be configured or modified to operate in Bridge Mode......then the Extreme can be setup to provide DHCP and NAT services correctly on the network.....avoiding the Double NAT error and other complicatons that arise when you try to run two devices both acting as routers on a network.

steftheref, you wrote:

"I read that the Extreme does not provide Guest Networking if it is in Bridge mode."

This is NOT true. In fact, it's the opposite. Guest Networking for the most recent Airport Extreme (802.11ac capable from 2014) ONLY works when your cable modem is in "bridge mode". This has been true for 3 previous networks I've set up with Comcast/xfinity internet service and AirPort Extreme/Time Capsules (both the new tall one and the old flat one) and it's true for the one I just set up tonight.

You need to call Comcast, or whomever your cable company is, and tell the tech that you want to use their modem as ONLY a modem, and not as a wifi router, because you have your own wifi router. Tell them to remotely configure your modem to be in "bridge mode". Once that's done, ask them to restart the modem again, remotely.

Now that it's in "bridge mode", plug your AirPort Extreme. It might start up and show green and be all peachy. If so, great. If not, do a factory reset and configure your AirPort Extreme or Time Capsule "as new". Sounds like a pain but it doesn't take much time. When you're all done, you should get the double green lights you're looking for. Good luck.

Mike, you may have misread. His statement was about the Guest network function not working when the Airport Extreme is in Bridge Mode, not the upstream router or modem.

But, your explanation brings up a good point - instead of configuring the Airport Extreme to do DHCP/NAT, where he would end up with a Double NAT and unpredictable results - He could instead put his carrier Modem/Router into Bridged mode, then have the Airport Extreme dish out DHCP. He'd just need to be aware that if the Upstream router has any directly connected devices like a wired PC for instance, he'd need to move that down into the Airport.

Mike,

Worked perfect! thanks! talked online to a comcast person. They put my modem in 'bridge mode'. I reset my Apple routers and my guest network now works! And my wifi seems to be working better now.

Maybe this helps:

AirPort base stations: About the Guest network feature - Apple Support

I have done the recommended fix: Call Comcast, get them to put the Comcast modem into "bridge mode" and use the Apple Extreme as a router with guest network. However, everytime Comcast "resets" their system and/or their is an electrical utility interruption (blackout) which happens fairly frequently in my rural area, the bridge mode is turned off (the default setting). Then I have to call Comcast again, some agents know how to do it, others don't and it is a major PITA. Are there any other solutions that people know of? Thanks.

Swap out the Comcast provided modem/router for a simple bridge mode modem (which will be in bridge mode at all times).

Check the Comcast website for a list of approved simple modems. Do not choose anything that provides a wireless option.....that is a modem/router or gateway type of device......which you do not need or want.

Buy your own modem and it will pay for itself in less than year compared to the monthly lease fee that you likely pay now.

Thanks for the suggestion. Their list of "approved" devices does not include any that are modems only. Unfortunately. (And to simplify my query, I did not state that I own my Arris cable modem/router--but Comcast controls the software on it and basically controls it).