Running the XB6 which is used for the Ignite TV service, or the Hitron CODA-4582 which is used to support gigabit service without the Ignite IPTV service? If you have the XB6, can you have a look at the bottom of the modem to check the modem model. It will either be an Arris TG-3482ER (Intel Puma 7) or a Technicolor CGM-4140 (Broadcom BCM-3390).
Are you running the modem in Gateway mode with a direct connection to the modem, or in Bridge mode with a router behind it, connecting directly to the router.
Were your tests run over ethernet or wifi? They should be run via ethernet to prove that the coax cabling and modem will support data rates over 900 Mb/s.