Modem/router to wifi-lan bridge?

i have an arris motorola surfboard sbg6782-ac cable modem gateway,

so,
uhh
long story short,

i have 2 modems,
going into
a tp link load balancing box (tp-link TL-r470t+)
going to
a gigabit switch
going to
all my computers and this sbg6782-ac via gigabit ethernet

my goal here is to use the sbg6782 to carry the ethernet lan over and blow out a nice wifi that the phones and laptops can connect too

AS WELL AS be apart of the LAN so i can still trade files from all the desktops and media servers and whatnot

id like to sit in the other room with a laptop connected to the sbg and have wifi internet and access to my lan desktop to stream my steam games and movies off of

(edit) i think ive got it working,
i hate the danm motorolas