Noob networking questions for better internet downstairs

Hi!

I have an asus rt-ax82u upstairs along with my modem. We used to have this downstairs but moved it upstairs for better signal when working from home. As a result, our internet downstairs now suffers

I have an ethernet capable coax downstairs. I was thinking about doing a MOCA set up and connecting it to this tplink wifi extender to act as the “router”.

Is this a good idea or is there better options to achieve a stronger signal? Im a complete noob when it comes to networking so any advice is super appreciated.