Nighthawk C6300 and FiOS Quantum Gateway AC1750 and Chromecast and other problems

Hi, ultimately i just want wifi to work in my house the easiest way possible that does not continuious die on me..  

I've spent  this month another 20-40 hrs trying to resolve the above three items (C6300, Fios Quantom Gateway, and Chromecast).. to various degrees of 'sorta-kinda-working-but not-really'

even searching the netgear forums for help only partially gets me there.. In that often times the advice says.. oh yea this does not work for the C6300, you need to do XYorZ but then the advice does not work (like to set up it as a AP mode. there is no AP mode on the advance tab, nor a "use other operating mode first".. 

anyway.. what id like to know.. whats best way to set these things up together.. note ive gone this route b/c after years of trying to get wifi in house (powerline adapters, extenders, etc, the netgear seem to be best option, this of course was before the orbi option)..   but i still have to turn off the c6300 so that my sony bravo tv does not loose connection 100+ times on a 30 min netflix show.. im assuming its b/c both routers are still on .. but i could be wrong. .and chromecast keeps dropping signal 

1) is there a way to have the Wireless of the Fios Gateway and C6300 play nicely together.. if so.. how  (screen shots would be great)

so, can someone walk me through how to get this up an running (possibly seting FIOS in brige, or C6300 in bridge, or C6300 in AP mode, or something else, and how to keep the Chrome cast from dropping the connection)  

thanks

steve