Nighthawk AX8 Bridging w/ Verizon-lose Internet when putting Ethernet into Netgear router

RAX80- When trying to bridge my Nighthawk router to my Verizon Fios router, I lose internet when I move the yellow Ethernet cord from my computer and put it into my Blackhawk router. I followed the directions and even did it with a Verizon helper on the phone.

The fios router is also my modem.