Xfinity XB6 Modem Slower in "Bridge" Mode?

I've got a 1Gbps connection and using my own router (Ubiquiti UniFi Dream Machine).  When using the Xfinity modem in "Bridge" mode, my speeds do not come close to Gigabit level (around 200-300Mbps).  When disabling "Bridge" mode, the MoCA connection enables by itself, which causes interference with my dedicated MoCA network. 

What is the best way to achieve full bandwidth and also configure with my MoCA network?