DPC3941B stops giving out Ipv6 prefix deligation -- factor reset required to restore functionality

Hello,

I think I have a DPC3941B cable model/gateway.  I have an IPv6 prefix assigned to our connection.  The cable model stops giving out these IP addresses after a time (short time).  If I reboot our router multiple times, the cable modems stops giving out this delegation.

Our other comcast connection is with the same cable modem/gateway in another building and it is not having any issues re-sending the prefix deligation after a router reboot.

We are using Barracuda's F series CloudGen routers.

This has been going on for over 1 1 /2 years I have been working closely with Barracuda's tech support and everyone has come up empty in terms of a solution.  Recently Barracuda had a firmware update (from 7.2 to version 😎 and I applied those to both routers thinking that perhaps somethings had been fixed and it would work correctly.

Still the office connection works great, but the other connection still didn't give out a prefix deligation to the router.

Out of shear desperation I decided to do a factor default reset of the cable modem.  When it rebooted, it handed out the prefix deligation right away.  I was thrilled and decided to get the rest of the router configured for IPv6.  After several reboots of our router, the cable modem again stopped giving out the prefix deligation. So I went right for the juggler and reset it back to factor defaults.  It started handing out our prefix deligation immediatly afterwards.

It is apparent that there is something wrong with the cable modem.  Yet support is charging me $100.00 to have a tech come out.  The guy on the phone lept rambling on about how they can't help us with our internal configurations, even though the problem is clearly the cable modems fault.

How can I get comcast to fix their equipment w/o charging me?

Thanks

Kevin