@Nlmw 

If you want the C1200 to extender the wireless network connecting wirelessly to the router use this setup: https://www.tp-link.com/en/support/faq/1555/

If you want to have an Ethernet cable from the Deco to the C1200, use this setup: https://www.tp-link.com/en/support/faq/2066/

@Nlmw 

Nlmw wrote

My access point will not set up. Scanning the SSID does not work. I see DECO
 as a connection but it won't set up and the light just keeps blinking. 

I Am Getting The Same Issue With me i Am Unable To Open My Website