Arris G54 modem-router can't access Xfinity IPV6

Hi,
After extensive troubleshooting with your Xfinity technical support representative with no fix, I was advised to contact Arris, the manufacturer of my G54 modem-router, for further assistance.

So, I did, and Arris support confirmed that my device is IPv6-capable and compatible with Xfinity.
Could you please reprovision my Arris G54 for IPv6?

• MAC address: You should have this information. However, if you don't, send me an email or text 
  Currently, my connection is IPv4 only—no IPv6 prefix delegation is being sent.
• To enable IPv6, please push dual-stack IPv6 with /64 prefix delegation.
  Thank you for your help