I used my secondary tplink wr840 as wifi extender with my primary router. Problem is when I used secondary router as wifi extender only one phone is connected with the secondary router but my another phone continuosly showing Obtaining ip address. As soon as I turned off my secondary router, my second phone connects with the main router but not connecting while using secondary router. But there is no issue when i used my secondary router as router instead of wifi extender. Tplink only supports 1 device for wifi extender or this is a problem of my secondary router?

Should I go for the warranty?