Set up my Xfinity Xfi TG4482A Modem as a bridge w/ TP-Link Archer C5400

Last night I tried to set up my Xfinity Xfi TG4482A modem in bridge mode.  According to the instructions it should be pretty straight forward:

1. Set modem in Bridge mode (Bridge Enabled)

2. Connect Wifi Router WAN port to an available Ethernet port on the Modem

3. Wait for Router to acquire IP Address. (Dynamic IP Address)

My Router never acquired an IP address and was never able to connect to the internet.  Clearly these instructions are not complete or accurate.  Anyone know what I did wrong?

Thank you!