The XB3 is not on the approved device list because it is not a retail device. The CM500V is an approved device. Whoever told you differently was misinformed. If you like, an employee here would be happy to help you get it provisioned, or you can call again.
1-800-COMCAST (1-800-266-2278) or 1-800-XFINITY (1-800-934-6489)
I know my CM500v is on the list as approved, but the dcp3939-XB3 doesn't show up at all.
The XB3 does not show up on the approved retail device list becuase it is not a retail device. It isn't for sale to the public.
. I am paying for BLAST tier and not getting it.
If you would like help from the community...
Start here: troubleshooting guide. If you still need help, please post
your equipment details (make/model of your modem/gateway/router) and a screenshot of your signal levels and your error/event log. Thank you!