RBR750 - can't connect to wifi

Hi I'm using RBR750 router as Access Point with 2 satellites. Recently i have been facing issues whenever I connect my iot devices to the Orbi and restart the device, it automatically disconnects and will not connect back to the Orbi. It shows the wifi name and everything but when try connecting it just won't connect. I have also replaced my RBR 750 but sill no use. Can someone help me solve the issue