ORBI RBR40 with R8000

I have been running an R8000 router and love it. Was having trouble with getting signal from far side of house and yard. Purchased a ORBI RBR40 with satellite. When first set up as a stand alone, the ORBI worked fine. However, now I want to run a network for personal and one for private activities. I have tried running the ethernet line from modem to my R8000 internet plugin and then running ethernet cable from R8000 #4 plugout (also have ethernet cable from R8000 #3 to older computer) to ORBI RBR40 internet plugin (also have ethernet cable from RBR40 #2 to newer computer). Should mention satellite is not setting up per instructions.

So end result is that I want newer computer to use RBR40 to handle private activities like home security system, with the capability to use shared peripherals on the R8000 network and the same with the R8000 handling personal activities like bill paying, etc...

If anyone can figure this out, please help me.