Why does my AirPort Time Capsule not back up any more?

The problem is Yosemite. It is a networking nightmare.

It has issues with networking like crazy.

There is a whole stack of stuff I would like you to try but as per your request for utter simplicity.. lets go one step at a time.

1. Did you reboot the whole network.. power everything down.. power up in order.. modem... TC.. 2min gap on each.. then computer.

You didn't list it as something you tried.. but you might have.

I just need to hear you say it failed.

2. I am not running Yosemite yet.. due to the aforementioned bugs.. I have a long list but I will not inflict that on you yet.

Do a soft reset of the TC.

This is a bigger deal than restart.. but not as big as full hardware or factory reset.

Get a toothpick, paperclip etc.. and press the reset button of the TC for 1-2 seconds.. no longer.

You then have 5min of unfettered access. Try the TM backup again.

3. Post a screenshot from airport utility.

I am not sure if you have done screenshots before.. get some practice doing specific areas not the whole screen.

Hold down Command + Shift + 4

The mouse will turn into a + .. place it on any side of the area.. hold down the mouse key and drag the rubber band to the opposite edge.

It will usually give a shutter sound.. and the file.

Screen Shot 2015-06-19 at 11.29.33 PM

will appear on your desktop..

In the forum here there is a little camera symbol.. click that and select your picture.. and post it.. easy peasy.

Pictures are worth 1000 words to us.. and you don't need to reproduce loads of screen info.

So here is what I want.. click the TC in airport utility and post the picture with the summary intact.

None of the info here is of any use to outside world.. so I give you mine.. you can see my serial number.. and I am not bothered at all.. It shows what I need..

You can then click edit and take screenshots of the actual setup pages..

eg Network.

4. On the computer there's one more relevant setting.

I want you to open the network preferences for ethernet and change the IPv6 setup to link-local only.. this helps loads. (wireless too if it is being used).

Don't get flustered by failures.. try once or twice.. then move on..

No luck with either of those we will need to move to full reset of the TC.

How stupid of me not to ask what the front led was doing.

Solid amber means it is dead hard disk.

But then I cannot understand how you are getting anything from Time Machine.. but it may be remembering not current.

Gen4 TC has some nasty issues with hardware.. but it is usually completely dead or completely alive.. yours is half dead (and not full booted because of the dead hard disk).

You cannot get any info or boot from it because it is not working.

Power off and leave it off for several hours . overnight.. I guess you are getting internet by connection to the main modem router by wireless.

After the TC starts up from cold.. immediately do a full factory reset.

Factory reset universal

Power off the TC.. ie pull the power cord or power off at the wall.. wait 10sec.. hold in the reset button.. be gentle.. power on again still holding in reset.. and keep holding it in for another 10sec. You may need some help as it is hard to both hold in reset and apply power. It will show success by rapidly blinking the front led. Release the reset.. and wait a couple of min for the TC to reset and come back with factory settings. If the front LED doesn’t blink rapidly you missed it and simply try again. The reset is fairly fragile in these.. press it so you feel it just click and no more.. I have seen people bend the lever or even break it. I use a toothpick as tool.

N.B. None of your files on the hard disk of the TC are deleted.. this simply clears out the router settings of the TC.

This will most likely do nothing because the TC needs replacement or repair.

Apple only replace if in applecare.. so it must be less than 3years old.. is it??

Many are now going over the 3years mark.

If you have DIY skills.. you can open it and remove/replace the dead hard disk.

https://www.ifixit.com/Device/Apple_Time_Capsule

Even if you merely disconnect the drive it should boot and run as an Airport Extreme of the same era.. but buy a 3 or 4TB disk and upgrade it could be worth it.

Ask any questions.. I have repaired a few hundred of them.

Give me the LED blink sequence after the factory reset..

It should go

Green 1 sec.

Solid Amber about 30sec-1min

Flashing amber. forever until setup is correct but normally just a few seconds then solid green.

The ethernet ports should all flash green within 1-2 seconds of switch on.. it is hard to watch both sides at once but try.

Tell me how it is ..

Less than a year.. you are saved!!

Take it back and get yet another replacement.

Perhaps it is better to sell this one straight onto ebay unopened and buy yourself something more reliable..