|Click on my name above in this response and read my “how-to” guide titled, “Add a second Router to your LAN”|
You will be using "Version 1" wherein you interconnect the two routers "LAN port to LAN port" and statically assign an IP to the LAN side of router2 (the downstream router).
I suspect you already have a port forward configured on the Linksys router to allow external traffic to pass through the router and access the cameras. You will need to copy that on the new router as well.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.