what settings are required to connect tc to charter cable modem?

I'm running Yosemite and have the latest Time Capsule. Moving from AT&T U-Verse to Charter for faster internet access, but I cannot get my TC to connect to the internet when connected to the Cisco DPC3216 modem. My TC is setup in Bridge mode which works fine for AT&T. When connected to the Charter modem, Airport reports no Internet connection.