Hi hopefully some one can help me.

I'm trying to connect my RE450 extender (located at the bottom of my garden out of wifi range) to my router in my house using a wired Ethernet cable , and then connect my chromcast/firestick to the eclztender via WIFI. 

something similar to below

house router ---------------------------  RE450  🛜   chromcast

                        (Ethernet cable)               (wifi)

can this be done , some videos says that I might have to change the IP address.