Although there is no good reason for it, the change of modem seems to always wreak havov.
Is the modem different?? Is it by any chance a modem router instead of pure modem??
I would always recommend doing a factory reset and start over.
That will do nothing to your backups but you will need to do the setup from scratch.. I recommend using new names.. as that helps things adjust to new environment.
Use short names, no spaces pure alphanumeric.
If the new box is a router bridge the TC.
How do I do a factory reset? Is my backup data 100% safe when doing so? Are there any other settings I shoukd be lookng at? Thanks for your help.
From the horses' mouth. http://support.apple.com/kb/HT3728
In simple terms.. hold in reset before you power on the TC.. power on with your third arm.. or get a friend to switch on at the wall.. keep holding until the TC LED flashes rapidly..
You can also reset via the airport utility.
You data on the hard disk is 100% untouched. To erase data you must choose that option from airport utility and confirm the action.
This should fix it.