Airport Extreme Unexpected Error when Extending

Odd things do happen.. For example my most recent attempt to extend did not work because the 5ghz was using a DFS channel. By jumping in and doing the setup manually it was fine.

Let me suggest once you try and the setup and it fails.. connect by ethernet to the Extreme .. still leave it extending by wireless.

There is a good chance the self generated IP 169.254.x.x will allow the computer to connect to the Extreme.. you can then discover the problem.. over wireless it will never work.. but over ethernet I have beaten it.

If that does not work do the whole setup manually over ethernet..

So reset the Extreme but make sure it is located near enough to the TC to get good signal.

Instead of using the normal setup wizard use configure other and put in the IP 10.0.1.1 which is what it will revert to.

Then fill out the name on the first tab.. base station with a password.

Make sure you uncheck setup over wan which will come up as error if on.

Then go to the wireless tab.. change to extend wireless and simply select the wireless from the TC which should be remembered on the Mac.

I suggest you select the 2.4ghz if the TC has different names on the two bands.

Then click update and it should work.

Post a screenshot if you have issues and we can help you track through it.

I am of a different opinion.

No offence to Bob..

I follow what he is saying but the times that I have run into trouble I have always been able to get out of trouble by using ethernet.

Note this is only ethernet from the computer to LAN port of the AE. You are still extending by wireless from TC to AE.

But ONLY ethernet can be used when no IP is picked up by the AE because it still can use self generated IP. Wireless cannot do this.

Suit yourself on this one.. But when you get in a hole with wireless.. simply repeating the exercise by wireless IMHO achieves nothing.. ONLY fixing it by ethernet will get out of the hole.

What info did you need on the TC setup? Isn't the TC just plug it in and turn on? I have no issues with the TC so I don't want to brick it by doing a reset. Then I'll be in a really bad spot.

The TC is the base to the network.. get anything wrong or difficult and when you try to extend it won't work.

Setup of the TC is MORE important than the AE. It has to work and for Catalina which has network problems galore then making the TC a simple as possible setup will help no end.

Anyway.. I understand the fear.. but you are not going to fix things without clean new setup. At least not on Catalina.

IF you have older Mac OS or even windows OS with airport utility and ethernet I could show you how to do it.

For now give me screenshot of your overall setup.

World symbol for internet.

Summary.. by clicking the TC icon.

Then click edit and do every tab (don't need disks).

Are you saying that connecting my computer to the AE via ethernet improve the setup process?

Only if the computer is also connected to the Time Capsule by Ethernet.

Makes no sense to have your Mac connect to the Time Capsule using wireless and then try to configure the AirPort Extreme using Ethernet.......because you are still relying on a wireless connection as part of the process.

In other words, if you want to use Ethernet for the setup, the setup has to be all Ethernet.

Please try the following:

Power off the Time Capsule

Perform a Hard Reset on the AirPort Extreme by powering it up for a minute or two, then holding in the reset button for 7-8 seconds. Release the reset button and allow a full minute for the AirPort Extreme to restart

Power off the AriPort Extreme

Power up the Time Capsule and let it run a few minutes

Power up the AirPort Extreme and run through the setup again. If you plan to have the AirPort Extreme connect by wireless to the Time Capsule, do not use an Ethernet cable to connect the AirPort Extreme to the Time Capsule

First thing to do is reboot / restart (i.e. power off and on again) everything.. and I mean.. EVERYTHING.. on the network starting from the modem.. all the way back.

It is best to shut everything off and then power up modem.. wait 2min then everything in sequence as it is wired or connected.. with 2min gap to allow each to be fully operational.

The computer also needs a full restart. And even turn off the airport utility and back on again. With Catalina.. trust NOTHING to do with its networking.

You will need to give us specifics to help. I would need to see screenshots of your TC setup.. and then as you go through the setup of the Extreme, show us every change you make so we can pick up any mistakes.

Do you have the TC setup with different short names on the two bands.. this is vital??

Do choose 2.4ghz only for the Extend. DO NOT USE 5ghz.

I also must say.. configuring wireless by wireless is akin to sawing off the branch you are sitting on.

It is REGRETTABLE that Apple dropped ethernet ports on their computers. Real ethernet that is. But it can be worth buying the appropriate dongle Thunderbolt to Ethernet.

Ethernet is still 1000% more reliable than wifi.