airport extreme

Last question first.

Can I connect the base unit directly to the internet service instead of using the Pace modem, or does it HAVE to be connected to the Pace?

No, because the Pace device is a modem/router or gateway device that is actually two devices.....a modem....and....a WiFi router..... combined into a single physical package. You might be able to turn off the wireless function on the Pace modem/router though, if you do not want to use the WiFi signal that the device provides. Or, you might want to reserve the Pace wireless for "guests" to use.

The AirPort Extreme is a router only......there is no modem on board.....so while you might be able to physically connect the AirPort Extreme directly to your Internet wall port, the AirPort Extreme would not be able to connect to the Internet.

However, when I connect the base unit (by connecting an ethernet cable from a Pace port to the WAN port of the Extreme) and the unit displays a green light (indicating it is connected properly and working), I do NOT see the base unit as a network to choose from in Settings/WiFi on my iMac,

If the AirPort Extreme was set up correctly, you entered a name for the wireless network for the AirPort Extreme to broadcast along with a password for the network. Do you remember the name of the network and the password that you assigned for the network?

If you do not see the name of this network when you click on the WiFi menu at the top of the Macs screen, then one or more of the following possibilities is likely true:

1) The Airport Extreme was not set up correctly.

2) The AirPort Extreme wireless radio is not working, or it has been disabled in the settings for the device.

3) Unlikely, but if you enabled the option on the AirPort Extreme to "hide" the network name, then the network will not appear when you click on the WiFi menu at the top of your Mac's screen.

Does your Mac have an Ethernet port that you could use to connect the Mac to one of the three LAN <--> Ethernet ports on the AirPort Extreme.......to check some settings that way?

If not, a Thunderbolt to Ethernet adapter is a mighty handy item to keep in your desk drawer.....so you can check things using a wired connection when wireless is acting up, or not working.

Thunderbolt to Gigabit Ethernet Adapter - Apple

Last question first again......

Since I am checking the settings in AirPort Utility app, this really isn't necessary is it?

To check the settings on the AirPort Extreme, you will need to be able to connect to the wireless network that the AirPort Extreme was setup to provide.

You told us that you could not even "see" the wireless network that the AirPort Extreme was providing....and if that is the case, then you won't be able to use AirPort Utility to check the settings of the AirPort Extreme.....because you won't be able to connect to the AirPort Extreme using wireless.

That is why we asked if you could use a wired Ethernet connection between your Mac and the AirPort Extreme......to be able to take a look at the settings for the AirPort in AirPort Utility.

The name I created for the base unit is Sully's AirPort Extreme.

This is the device name that you selected for the AirPort Extreme.

You would have also entered or specified a wireless network name during the setup of the AirPort Extreme and specified a wireless network password as well. But, if you can't even "see" the wireless network to select it, then something has gone wrong.

So, the options at this point are to used a wired Ethernet connection from your Mac to the AirPort Extreme to take a look at the settings......or......if this is not possible, the only other option would be to start over again and try to set up the AirPort Extreme again.

However, we are confused when you say that you checked the settings for a hidden network using AirPort Utility. How did you do this if you cannot see or connect to the wireless network that the AirPort Extreme was providing?

Are you saying that you really can see the settings for the AirPort Extreme when you use AirPort Utility......despite the fact that you cannot "see" the wireless network?

If this is the case, then we are really confused, since you would not normally be able to see the settings in AirPort Utility unless you were connected to the wireless network signal from the AirPort Extreme......which you have said that you cannot even "see".

it was set to 'Extend a Wireless Network'.

"Extend a wireless network" is a setting that would be used only if the AirPort Extreme were connecting to another Apple AirPort router using only a wireless connection.

"Create a wireless network" is the correct setting whenever the AirPort connects to a modem or another modem/router using a wired Ethernet cable connection. So, this would be the correct setting to use with the Pace modem/router.

1) Set Security to WPA/WPA2 Personal,

A better and more secure setting would be WPA2 Personal only, if all of your devices will connect using that security level. WPA/WPA2 Personal is not as secure as WPA2 Personal.

2) It also recommended that I set the Router Mode to 'Off (Bridge Mode)' within the DHCP and NAT setting in Advanced Options.

This is the correct setting for the AirPort Extreme.....since you do not want two devices both trying to provide DHCP and NAT service for the same network. This can cause IP address conflicts and a host of other issues as well.

"Off (Bridge Mode)" will allow the Pace modem/router to provide DHCP and NAT connections on your entire network....both the Pace and AirPort. The AirPort can still provide a wireless network when it is set up in "Off (Bridge Mode)".

If the Pace device were a modem only......not a DHCP and NAT router.....then the AirPort could be configured to provide DHCP and NAT for the network. I doubt that AT&T will allow you to set up the Pace as only a modem though.

I reviewed the installation directions for the AirPort Extreme before I tried this forum and the directions were not this specific.

Apple has always had a tendency to try to make things overly simple when they really are not. With a new product, you have 90 days of free phone support from Apple, so you might want to take advantage of this when you can.