I have own Cable model Netgear C7000V2;

Root: C7000V2 (Cable modem/router) -----> R7800 (Router)

My business cannot afford a downtime.  Did not want to change anything major on the C7000v2 (Root modem)

So, Before installing Deco M5, to test it out, I have configured another router Netgear R7800. 

The second router does not use DHCP, LAN port from C7000 is connected to LAN port of R7800.

Root C7000V2 is  IP 192.168,0.1 and R78000 is IP 192.168.0.2

Ethernet and WIFi everything is working fine.

Now, if I simply swap R7800 with Deco M5 main  and assign it IP= 192.168.0.2

and no DHCP, will it work?

 Do I need to use "Bridge mode" on the Root modem?  

Thanks a lot in advance,