Netgear Nighthawk Router

I have a question I hope I can get answered.
My son has xfinity cable at his house. He has a Netgear Nighthawk router and Ring cameras. One of the cameras is on his steel building but it doesn’t pick up the WiFi very well. I got him a TP link deco mesh system but not sure if I’m missing something when connecting it.

I used an Ethernet cable and connected his Netgear router to the one TP link router. I placed the other TP link device in the room that is closer to the steel building.
I plugged them in but they were both flashing blue and never connected to his Ring cameras.

Is there something in the Ring camera settings or a setting within the Netgear that needs adjusted?

I hope I explained myself clear enough 🤯

Thanks for any help!