tryin to connect a tp link powerline to a n300 wifi extender through the ethernet cable

[Basie]

Ive recently purchased a mobile broadband huwaei device which has wifi.  

I have also recenetly bought a Negear n300 wifi extender which allows you to connect to the huwaei device via wifi and then you are able to connect an external device via the ethernet port. 

I would like to use my Tp-Link powerline system to distribute the internet from the n300 throughout the house, although i'm finding that it wont let me.  Does anyboby have any idea why the tp-link and n300 wont just talk to each other to distribute.  

i have the issue that the wifi wont reach all corners of my home, as i want the huwaei device in my kitchen to use alexa.  I don't really want to buy 5 or 6 n300, which probably wont reach ny ways.  The TV boxes that i have must be connected to ethernet.  as does my mycloud.

any suggestions?

[Basie]

to clarify the tp-link and n300 would be connected via a ethernet cable.  i tried the tp-link which was previously connected to my BT router.