After changing my network hub, I'm having difficulty connecting my Time Capsules

Since you reset the Time Capsules back to factory default settings, you will need to set them up again before AirPort Utility will recognize the devices.

Keep one Time Capsule powered off until the other has been set up and working.

Click the WiFi menu at the top of your Mac's screen

Look for a listing of New AirPort Base Station

Click directly on Time Capsule

That will start up the setup "wizard" to guide you through the new configuration process

Once the Time Capsule has been set up again, it will appear in AirPort Utility

Set up the other Time Capsule the same way

Have another try.. but do one at a time.

Using two airports with both unconfigured might be confusing the system.

The TC should be close to the computer so it can pickup its wireless signal easily. Otherwise it could simply be swamped by the other wifi routers around you.

If it does not show up on the Computer try iOS version airport utility which is somewhat better.

You also might try just opening the airport utility on the computer.. and click on the Other WiFi Devices (1) which should show up.

If you don't find anything with those methods.. grab a thunderbolt to ethernet adapter.. assuming your computer is lacking that most essential port.. and you don't have another computer or even lowly PC to do this.. when you change to ethernet you have to change the airport utility to ethernet as shown above.

Here is what I got.. my old laptop actually ethernet port but I have a thunderbolt dongle as well.

Setup will be different of course.. this is totally isolated.

Once I finished i plugged a cable from wireless router to the TC.. and once I flipped over to thunderbolt..

And ignored the double NAT error.. it all worked fine.

There is one strange issue .. if you main router happens to be using a 10.x.x.x address the TC will not be happy in double NAT.. no problem with standard bridge mode though which you should be using.

This is in complete isolation from the internet?

So you have the computer plugged into the TC via your adapter and nothing.. that would be very odd.

Does the Thunderbolt dongle work? Plug it into your main router.. do you pick up an address and can do internet ok?? If so the ethernet is working..

Go back to the TC.. make sure you plug into a LAN port..

Do a full factory reset.. i.e. power off.. hold in reset and power on again without releasing reset for about 10sec until front led flashes rapidly.. It should definitely show up.

No luck.. check your ethernet is set correctly to DHCP. Set IPv6 to link-local only.. this is important.. it should not be off or automatic.

The computer should definitely be getting an IP of 10.0.1.2 and the green light on the ethernet port you are connected to should be on.

OK that is good news..that it now can be configured.

Is there something I can do to make it realise it's the same disk or will I have to delete the whole disk and then do a full backup again?

Even if you gave it the same name things do get confused..

You do not need to delete the current backup.

In Time Machine all you need to do is select the "new" disk.. as the target for your backup.

This is from an earlier post I did. Time Machine has lost connection to a backup on a different brand router but that makes no difference..

TM counted down 120sec to start a backup.. and then mounts and checks the disk.

You will see TM now goes into a very long period of preparing the backup.. what has happened is that TM discovered the existing backup.

The log shows why.. it is doing a deep scan.

Starting manual backup

Attempting to soft mount network destination URL: afp://ray-local@RT-AC3200-82F0._afpovertcp._tcp.local./Backups.backupdb

Mounted network destination at mount point: /Volumes/Backups.backupdb using URL: afp://ray-local@RT-AC3200-82F0._afpovertcp._tcp.local./Backups.backupdb

Checking for runtime corruption on /dev/disk2s2

Disk image /Volumes/Backups.backupdb/z87proimac.sparsebundle mounted at: /Volumes/Time Machine Backups

Network destination already mounted at: /Volumes/Backups.backupdb

Disk image already attached: /Volumes/Backups.backupdb/z87proimac.sparsebundle, DIHLDiskImageAttach returned: 35 (Resource temporarily unavailable)

Disk image /Volumes/Backups.backupdb/z87proimac.sparsebundle mounted at: /Volumes/Time Machine Backups

Backing up to /dev/disk3s2: /Volumes/Time Machine Backups/Backups.backupdb

Forcing deep traversal on source: "asusz87pro" (device: /dev/disk0s2 mount: '/' fsUUID: 2BB3E4A1-CE4C-350F-B8E8-E69BB22A5DE1 eventDBUUID: 1A326CD6-8C1A-467B-9FB1-3A628959CEFA)

Deep event scan at path:/ reason:must scan subdirs|require scan|

Running event scan

initial consistency scan for '/'

Depending on the size of the backup and speed of the network connection. (if it is network target..) it can take a long time..

It took 20min to complete check of 120GB boot drive backup on fast network.. multiply your disk size by the time. Divide by whatever fraction your network speed is less than 1Gbps. For wireless divide by another 0.5 to include reality over hype. (Maybe 0.1)

Assuming the scan comes up Apples.. (used to mean all good A+)..

The backup will proceed to do a simple incremental.

The log will show now what has happened.

Finished scan

Saved event cache at /Volumes/Time Machine Backups/Backups.backupdb/z87proimac/2018-01-02-113204.inProgress/62C502BA-C5CB- 488F-AB71-E0D44D3EF25F/.2BB3E4A1-CE4C-350F-B8E8-E69BB22A5DE1.eventdb

Will copy (152 MB) from asusz87pro

Found 810 files (152 MB) needing backup

443.7 MB required (including padding), 287.52 GB available

Copied 1129 items (152.3 MB) from volume asusz87pro. Linked 4637.

Created new backup: 2018-01-02-115130

Starting post-backup thinning

Deleted /Volumes/Time Machine Backups/Backups.backupdb/z87proimac/2018-01-01-104923 (62.1 MB)

Post-backup thinning complete: 1 expired backups removed

Backup completed successfully.

Ejected Time Machine disk image: /Volumes/Backups.backupdb/z87proimac.sparsebundle

Ejected Time Machine network volume.

And the previous history will be noted as per before you reconfigured.

If this doesn't work for you we need to get harsher and do some more dirty stuff.

As a btw my recommendation now to everyone on Sierra and later OS.. do NOT trust Time Machine.. it is unreliable at best.. broken at worst.. and you can discover it wasn't backing up properly anyway without any indication.

Use a third party like Carbon Copy Cloner..

If you really must use Time Machine use it to local drive plugged into the computer .. eg USB. Since Sierra network backups are too problematic.

How to reset Time Machine.

To go a step further you can start Time Machine afresh.

Apple made no provision to do this.. so you need to get down and dirty.

Delete TimeMachine.plist

Macintosh HD > Library > Preferences > "com.apple.TimeMachine.plist"(delete this file or rename it)

In Finder locate the main Library and Preferences. (you might need to turn on view hidden files).

I renamed the existing file old.. and reboot the computer.. when you start Time Machine again via preferences it will recreate the plist.

Then just configure Time Machine to use the previous disk.. it will still take a long time to deep scan the existing backup but should continue the backup.