Hitron moca adapter and ppc-9m-uu

I have xfinity with one main box and three stb's.  It appears that the main box uses moca to connect to the three stb's at 1175 MHz.  First device on premise is poe filter and PPC-9M-UU.  I am attempting to add hitron omca adapters on same network using high band at 1400 MHz.  When I use plain splitters, I can get hitrons to link, but as soon as I connect thru PPC amp/splitter the hitrons disconnect.  Any suggestions?