Problems Enabling Guest Network

The Guest Network feature will not work correctly......unless......the Router Mode is set for DHCP and NAT under the Network tab in AirPort Utility.

Based on the information that you have provided, you might have the Router Mode set to "Off (Bridge Mode)". The Guest Network will not work correctly with this setting.

Check on that and report on your findings. Do NOT change any settings at this time, as things may not work correctly if the device that you call your "modem" is really a modem/router or gateway. Another way to say the same thing would be to state that the Guest Network feature assumes that you have a simple modem........not a modem/router or gateway.

A simple modem has only one Ethernet port and will look similar to the example below:

You will need to check with your Internet Service Provider (ISP) if they provided the modem/router to you to find out whether it is possible to change the wireless password for the device.....and if it is......"how" to do this.

Another option would be to ask your ISP if they can provide you with a simple modem.....the kind with only one Ethernet port like the example that you see below.......to replace the modem/router that you are using now.

If they can.......then.....you will be able to set up the AirPort router correctly to provide both a "private" and "guest" network with separate names and passwords for each network.

Unfortunately, more and more ISPs are forcing their customers to use the modem/router that they provide, so the last "option" that is mentioned is really more of a "maybe".

Kind of a Catch 22.

The Guest Network will not function correctly unless the Router Mode is set to DHCP and NAT.

But......enabling DHCP and NAT will mean that you will now have two routers both trying to control the network......the AirPort and the device that you call your "modem"......which is also a router. Not good.

Apple assumes that you have a simple modem, and you don't.

When you enable DHCP and NAT on the AirPort with the type of modem/router or gateway that you have, that will introduce a network error known as Double NAT, which can slow down your Internet connection and possibly not allow some web sites to connect. The AirPort will blink amber to complain if you try this, and a message will appear telling you that the AirPort needs to be in a Router Mode of "Off (Bridge Mode)" to correct the problem.

I would NOT recommend that you try to change the current correct settings on the AirPort to incorrect settings to possibly allow the Guest Network to function.

Since you have another router, why not use the WiFi from that device for your "guest" network?

Or, depending on the capabilities of your modemr/router or gateway, it might be possible to set it up to act only as a simple modem. Then......the AirPort could be configured in DHCP and NAT to allow the Guest Network to work correctly.

Not all modem/routers or gateways can be set up as a simple modem though. That would be a question for your provider if they furnished the "modem" to you.

That info is usually on a label on the bottom of the "modem". The user name will usually be something like 192.168.1.1 password might be the serial number of the device. It varies.