Motorola MB8611 and Firewalla Gold Router. DHCP not work on Xfinity?

I've used NetGear and LinkSys routers for seven years on ComCast Xfinity.  Acquired a Firewalla Gold router/firewall to tackle a problem where I have to cycle power on everything weekly to keep Siri talking and the doorbell working.

I can't figure out why your network can't accept DHCP from a storied company like Firewalla connected to a Motorola modem (that has no router).

Fearing a hardware issue, I put the LinkSys modem back, it came right up.  Took screenshots of the network / DNS settings. 

Swapped in the Firewalla and DISABLED DHCP, put in a static IP, netmask, gateway, both DNS servers.

Worked brilliantly until 8:30AM the next morning.   Not supposed to switch out of DHCP mode?

I am able to use your website to reboot the modem all day..   

Connecting to AWS?   Alas, my Xfinity service is apparently in Zombie mode.  It's alive but nothing works.

So, any router works as long as it wasn't designed by Ex-CISCO engineers?

Robert [Edited: Personal information]