Cannot connect to TC after swapping out modem, although wifi is working fine.

It is set up, activated, and and wifi is working through my Time Capsule (802.11n 1TB).

The last bit of this.. wifi is working through my TC.. no sorry that is not possible.

I have not tried a reset on the TC...

TC must be plugged by ethernet into the main modem. If it is a router. Then the TC should be bridged.

But whichever way it is working you cannot remove ethernet from the TC.

TC should also create a wireless network and the Mac should connect directly to the TC otherwise on Yosemite or any of the later OS it will be unreliable and disappear from the network.

So reset the TC.. no files are lost and redo the setup.

I would recommend that you first find out why that amber light is flashing before you reset the TC.

If you agree.......

Open AirPort Utility on your Mac (Finder > Applications > Utilities > AirPort Utility)

Click on the picture of the Time Capsule

In the smaller window that appears.....look for Status

What is the message next to Status?

If there is a simple setting that needs to be changed, then you can avoid having to reset the Time Capsule and starting all over again.

IF.....the Time Capsule does not appear when you open AirPort Utility......then a reset of the Time Capsule will be needed.

The only thing that I changed was swapping my old modem with a new one supplied by the cable company.

There is an old saying in networking that goes something like this:

Make just one small change on a network........and everything else will change.

So, you will need to reset the TC and start all over.

I have had exactly the very frustrating experience you have had. Was using a Comcast modem (no router) for almost 4 years flawlessly. Comcast sent out a new modem that also has a router. Total confusion! TC will not back-up, can't be seen from the Comcast network. I can see and connect to the TC network, but no service. Tried bridging the Comcast router--nothing worked. Reversed the bridge, Comcast working. Cannot any longer perform backup to the Airport with TC software.. (remember worked fine 4 years). Can easily backup to external hard drive with Time Capsule software if plugged into usb port.

I purchased an Arris TM722 G telephony modem (no router) from Amazon, and will try to set it up when I have time. Will let you know if you wish.

If you call Apple support.....not a bad idea, in my opinion.....they will have you reset the Time Capsule.

The bottom line at this point is if you cannot open AirPort Utility, see the picture of the Time Capsule, click to select the Time Capsule, click Edit in the smaller window that appears, and then see the next window with tabs at the top for Base Station, Internet, Wireless, Network and Disks.......like the illustration below.....then you have no option at the present time, but to reset and try to start all over.

Does the new "modem" have only one Ethernet port on the back of the device......like the example below?

Or, does the "modem" look more like the example below of a modem/router or gateway device.....which you do not need....since it is making things more difficult to get the Time Capsule set up?

Frankly, the odds are stacked against us as far as being able to get the Time Capsule working without starting all over again.....because the Time Capsule is likely retaining some old settings that it needed to connect to your "old" modem.

We said that we would attempt to get you going again without having to start all over. We can offer no assurance at all that this will work, since every situation and every modem is different.

If it does not work, then the only option that you will have left is to start all over again and setup the Time Capsule again from scratch....like you did the first time that you set it up originally after you took it out of the box.

There should be an Ethernet cable connectiing from one of the LAN <--> ports (there are probably 4 LAN ports on the modem/router) to the WAN "O" port on the Time Capsule.

Open up AirPort Utility, click on the Time Capsule and click Edit to display the tabs at the top of the screen again.

Click the Internet tab at the top of the window and make sure that the setting for Connect Using = DHCP

Click the Wireless tab and verify that the name of your wireless network appears correctly

Click the Network tab and make sure that the setting for Router Mode = "Off (Bridge Mode)"

Click the Disks tab and make sure that there is a check mark next to EnableFileSharing

Click the Update button at the lower right of the window and give the Time Capsule a full minute to restart

A green light on the Time Capsule would be a good thing to see.

Connect to the wireless network that the Time Capsule is providing and make sure that you can connect to the Internet that way. Check other devices as well. If you have any devices that are connecting to the Ethernet ports on the Time Capsule, check to make sure that those devices can get a good Internet connection as well.

Post back on your results and we will continue to get Time Machine set up again next.

Lucky you! Nice work.

So, Time Machine backups are working as well?