TC Will Not Connect to Wired Devices

Question

I have a brand new Time Capsule.  All was working fine until this past weekend.  The problem is that I can only connect wireless devices now.  Wired devices do not seem to be recognized by the time capsule.  This is the case even for devices that have IP addresses reserved using their MAC address.  For example, I have a wireless access point with a reserved IP address, as well as AppleTV with a reserved address.  Both are connected to the Time Capsule by ethernet cable.  It seems that the Time Capsule will no longer connect to either of them.  I also have two VOIP routers that are connected to the Time Capsule and share a single router port on the TC via an ethernet switch.  Neither of these is able to establish an internet connection, as they do not seem to be recognized by the TC either.
Wireless devices seem to be connecting just fine, whether they have a reserved IP address or not.  For example, my printer uses a reserved IP address to connect via wireless and I am able to connect to its web interface using that IP address.  I cannot connect to my wireless access point using the reserved IP address, however, and it is hardwired.  So hardwired devices don't seem to be being assigned IP addresses by the router--even if they have IP addresses reserved for them.
I actually thought this was a problem with the TC and, as I had purchased this TC only a couple of months ago, I took it to the Apple store over the weekend and described the problem, and they swapped it out for a new one.  Same issue with the new one, however.  So it doesn't seem to be a hardware issue with the TC.
The strange thing is that this setup was working perfectly, and all of a sudden, it just stopped working, although I didn't change any settings.  Of course, I've rebooted the TC multiple times without success.
Any thoughts on how to resolve this issue would be greatly appreciated.

Answer 1

I would factory reset and start over.. start with the very simple network. Do not worry about your assigned IP to start with. Let everything just pick up IP dynamically.
Your modem, the TC and one wired device, plus wireless connection.
Do the setup of the TC.
You must setup ipv6 to link-local to get it talking to the TC correctly.
I strongly recommend you keep all network names as simple as possible.
Short, 2-10 characters. eg. TC name TCgen5
2.4ghz wireless name TC24ghz
5ghz wireless name TC5ghz (use different name here until you sort this)
Make sure the TC can communicate with a single device over ethernet plugged directly into it.
Then add the next part of the network. Make sure nothing else is taking the NAT router role, as it sounds like you have multiple routers in the network. Make sure as you add each device it gets an ip from the TC. And make sure you can ping it on the network.
If you run into trouble.. Put something else into the main router role, and see if that works ok. You can run the TC in bridge and see if that works.