Router problem

[Ergel]

I am trying to daisy chain two routers from my modem.
My setup is - I have a modem in my office, it has a hardwire to a router (router A) on the main floor of my house. Internet from this router is working great, however it doesn't reliably reach my attic. I have a hardwire running from router A to the router in the attic (router B). However, when I plug router B into the jack in the attic - the internet light is red and it doesn't pick up the signal. If I plug a computer into the jack - it connects fine. If I plug router B directly into router A, it also connects fine. The issue is when I plug in router B into the jack which is hardwired into router A.
What could possibly be the problem?

[stooges44]

If you can plug a computer into the jack in the attic and it connects, why do you need the router in the attic?

[ExGingi]

Post pictures of the router's backs. Also, can you connect to the attic router without it being connected to the other router? It might be a settings issue, running two DHCP servers on a single network is recipe for problems. How is your second router set up?

[Ergel]

If you can plug a computer into the jack in the attic and it connects, why do you need the router in the attic?

My bedroom is in the attic, plus we have smart lights and things up there

Post pictures of the router's backs. Also, can you connect to the attic router without it being connected to the other router? It might be a settings issue, running two DHCP servers on a single network is recipe for problems. How is your second router set up?

DHCP is turned off on router B. Set a static IP for router B on the same subnet, but not in router A's IP range

[Ergel]

Thanks all. I reset both routers and started from scratch. Looks like I got it to work