Comcast router, firewall issues, that is linked to DHCP not working

A month ago, we upgrade or business services which in turn Comcast installed a new router.  This was the worst mistake I have made in a while.  We use the service to provide guest Wi-Fi access.   All the router is supposed to do is provide internet service and DHCP addresses.  I have a complete Cisco wireless network and Cisco Firewall so there is no other services needed from the router.  When the router was first installed, we had to hard boot the router twice a day.  The reason for having to reboot was that the router stopped providing DHCP address.  The issue was not due to available leases it was something else.   After hours and hours on the phone with support and some Googling, I have the router running much better, but still not good as we are still having to reboot it a couple times a week.  The one thing that really helped was to fully disable the firewall. Well, I thought it was fully disabled, but today when the router stopped providing DHCP address I was able connect to the router before we rebooted it.   Looking at the logs I can see that the firewall is not completely disabled as there are firewall logs.   

Here are the logs I see:

FW.IPv6 INPUT drop, (###) Attempts, date and time

FW.IPv6 FORWARD drop, (##) Attempts, date and time

My question is how do I completely disable the Firewall?  Do I have to call comcast to get this done? 

My other statement / question is why the explicit can't Comcast provide a router that allows admins to manage DHCP better.  There is no way to remove DHCP leases. There is no way to turn off DHCP v6. That is the most frustrating thing, there are no private network in the world that needs to use DHCP v6.  I just don't understand why?