Moca support with gateway xb8-t

I tired to call customer service, but that didn't go as planned as its almost impossible to get someone on the phone unless you tell the automated system you want to close your account, and ¯\(ツ)/¯. Anyway from research I see that my gateway has built in moca.  I purchased moca adapters which I can only get them to work if I hook up 1 adapter to the ethernet port on my gateway.   To my understanding if your modem has built in moca, you shouldn't need to do this.   The instructions I found to log into the modem to confirm moca is turned on just show me a screen that says to download the Xfinity app which only allows me to change a few wifi settings.    My question is 

* Should I need a moca adapter connected to my gateway if my modem supports moca?

* How can I conform moca is turned out without being able to speak to customer service?

It looks like Xfinity installed a filter at the external entrance where the line is entering the property.   I am also using MOCA rated filters that came with the moca adapters.   There are no other splitters, the line goes directly from my attic to the room where I want the wired connection.