Lost created network when changing Airport Extreme base station from "Create" to "Extend"

Thanks for the confirmation.

For now, please power off the two AirPort Extremes that were set to "extend" the previous network, so we can concentrate on getting the "main" AirPort base station working correctly again.

I assume that you have still have the "main: base station connected to the Spectrum router as it was before.

Power up the "main" base station.....if it not already on....and let it run for a minute

Then, hold in the reset button on the back of the AirPort Extreme for 8-10 seconds and release

Allow a full minute for the "main" base station to restart to a slow blinking amber light status

If you are using a Mac, open up AirPort Utility

Click on the Other Wi-Fi devices button

Click on AirPort Extreme xxxxxx

AirPort Utility will now connect to the main base station

After a few seconds, a screen similar to what you see below will appear, except that you will see an AirPort Extreme displayed

Network Name........Type in the name of the wireless network that you want the AirPort Extreme to broadcast

Note.....you can use the same name that you used before or a new name if you wish

Base Station Name......Type in a name that you want to call the AirPort Extreme device

Password.....Type in a password for the AirPort Extreme base station and wireless network

Verify....Type in the same password to confirm

Click Next, and AirPort Utility will set up the main base station for you

Should be a green light on the AirPort Extreme in a minute

Test using your Mac to make sure that it can connect to the new network that you created

Post back on your progress and we will continue with the setup of the extending AirPort Extremes

When I changed the Airport Extreme (2017) base station WiFi network name & password (from previous homeowner set up) I lost connectivity to the 2 other Airport Extreme units that were acting as wireless extenders of the old network.

That loss of connectivity would be expected, since the 2 other "extending" AirPort Extremes were still looking for the "old" wireless network that the main AirPort Extreme was previously producing. But....that previous wireless network no longer existed. So, the 2 AirPort Extreme extenders were lost and did not know how to find their way.

I figured I needed to have the remote Airport Extreme get the same network name & Password so I changed in the Airport Utility the option from "create network" to "Extend Network".

If you made this change on the "main" Airport base station (which is what I think you are saying).....that was not the correct setting.

After all, you just told us previously that (The base station worked fine with the new network name/password), but it appears that you changed the setting on the main AirPort base station to "Extend".....when "Create" was the correct setting.

As it stands now, the main AirPort Extreme is not configured correctly, so it too is "lost". That's why it has disappeared in AirPort Utility.

Before we tell you you how to fix everything, I just want to confirm that what I have picked up so far from you is accurate. Did I get what you are saying and describing above correct?

Please post back to confirm so we can begin to fix things.

If you are OK with using the same password for the base station and wireless network......this does make things simpler, with less chances of an error......you can proceed with the setup of the extending AirPort Extremes.

My preference is to set up an extending AirPort by temporarily moving it to the same room or close proximity to the "main" base station......if possible. Then, once the AirPort is set up and working, you can power it off and then move it back to the location where it will be needed.

If it is not convenient to move the extending AirPorts close the main base station for the setup, you can go ahead and set them up at their respective locations.

Power up only one of the Airports that will be extending the network

Hold in the reset button on the back for 8-10 seconds and release

Allow a full minute for the AirPort to restart to a slow, blinking amber light status

Open AirPort Utility

Click on Other Wi-Fi Devices

Click on AirPort Extreme xxxxxx

AirPort Utility will take a few seconds and then display a screen that looks similar to the example below, except that you will see an AirPort Extreme pictured

Base Station Name......Type in a device name that you want to call the AirPort Extreme....maybe something like Airpor Extreme Ext 1....for example. Then, click Next

The next screen will look like this:

You will see an AirPort Extreme and the name of your wireless network displayed

When the next screen appears to confirm that setup is complete, click Done.

If you moved the AirPort Extreme close to the main base station for the setup, you can power it off and move it back to the location where it is needed and then power it back up again.

Then, set up the second AirPort Extreme the same way, giving it a device name that makes sense for your network.

It is important that the second AirPort Extreme is located closer to the main base station than the other Airport Extreme for the setup, because you want the second AirPort configured to connect to the main base station and not the other AirPort Extreme.

I have not added a password for the new network yet though it seems

Yes, you have. It was the password that you entered during the setup. You would not be able to connect to the wireless if you had not set up a password for the wireless. As I described above, this password is used for the wireless network and for the base station. Here is what I said:

Password.....Type in a password for the AirPort Extreme base station and wireless network

If you are asking if you can set up a separate password for the base station, the answer is "yes", but it requires a few more steps. You don't really need to do this, but you can if you want. Let us know.....then....we can set up the "extending" AirPort Extremes.

Two things:

1. The depiction of the AirPort connections in the AirPort Utility is not always accurate.
2. To be sure that your extending base stations are optimally located for providing the best bandwidth performance, please take a look at the following user tip article: AirPort - Optimal Base Station Placement - Apple Community

For the second item, you may find that a small location adjustment will make all of the difference.

Nice work, glad that we could help.