The error message when trying to connect either 2.4G or 5G Ext network is that : Cam't connect to network" . Also, the router password for 2.4H and 5 GHz are same.

I have installed RE 550 , connected to gateway. I am able to connect to Extender network using my router password. However, ia m unable to connect to extender network on my PC laptop. Plase advise