Airport Time Capsule keep dropping from my network

Unfortunately, this type of error is common with Yosemite (10.10.x), since there are still a number of networking bugs in the operating system.

The following might help this issue, but there are no guarantees:

On your Mac, open System Preferences (gear icon on the dock)

Open Network

Click on WiFi on the left side of the window to highlight it

Click Advanced at the lower right side of the window

Click the TCP/IP tab

Make sure that the setting for Configure IPv6 is set to Link Local Only

Click OK

Click Apply in the next window that appears

Then, repeat the exact same sequence by clicking on Ethernet to highlight it and following the same steps

Next, Open System Preferences again, if it is not already open

Open Sharing

Make sure that the name of your Mac appears correctly here, and that there is not a (2), (3), (4), etc appearing after the name of the Mac. If there is, edit the name so that it appears correctly

Restart your Mac

Power off the Time Capsule, wait a few seconds, then power it back up again

Post back on your progress in having the Time Capsule appear in AirPort Utility, as another setting on the Time Capsule needs to be checked and likely changed.

Not sure what you are looking for, but the Timed Access option in AirPort Utility will allow you to individually control the times in which any wireless device will be allowed to connect to the network.

For example......

Kid 1's iPad could connect to the wireless network Everyday.......Between......5 PM and 9 PM.

Kid 2's iPhone could conned to the wireless network Everyday......Between.......4 PM and 10 PM

Kid 3's iPad could connect Everyday......Between.....9 AM and 6 PM

At the same time, your devices will be able to connect at any time that they want

Please start another post if you need more information about Timed Access.

Yosemite has some real problems, unfortunately.

When you can "see" the Time Capsule again in AirPort Utility......and that might require powering the network off, then powering back up.....you need to check an IPv6 setting in AirPort Utility.

Open AirPort Utility and click on the Time Capsule icon

Click Edit in the smaller window that appears

Click the Internet tab at the top of the window

Click the Internet Options button at the bottom of the window

Make sure that the setting for Configure IPv6 is set to Link Local Only

Click Save, then click Update

My iPhone recognizes the APTC but the iMac keeps dropping it.

Funny....or maybe it is really not so funny......but AirPort Utility on an iPhone or iPad is a much better application than AirPort Utility on a Mac, so you might want to make the iPhone your primary administration device.

I've had the very same problem and removing AppLe's Server app solved it completely for me (with the loss of stock server functionality as a side effect, obviously)...

By the way, this Server app on one Mac also affected other Yosemite Macs on the same private network to loose access to the Time Capsule...