Ethernet

Hello @maprik !  I use and recommend this LinkUp Cat 8 22AWG:

https://www.amazon.com/dp/B087C9VZHT?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_3&th=1

It is much better than cheapo  cable and won't break the bank.  I have it on two runs of 25 and 30 feet.  Also, don't use cheap connectors or wall plates.   I run the cable through the wall (plate) and make direct connections if possible.  If you need a junction use these from JCAT:

https://jcat.eu/product/net-isolator-gigabit-network-isolator/

I find these difference's matter.  HAPPY NEW YEAR!

Yes, bypassing the Wi-Fi receiver often yields benefits because you’re bypassing its processing and any noise it generates.  If I was you I’d get an Eero Mesh setup and run a better/shorter Ethernet cable from that to your streamer — being able to use a better Ethernet cable can yield big benefits as opposed to using a cheaper/longer one.  Just my $0.02 FWIW. 

Honestly modern Wifi is really good, the biggest issues I know of are related to contention on the same Wifi channels and RFI noise. 

I always suggest users get a free phone or laptop Wifi analyzer to help them see their Wifi neighborhood.  Pick an unused channel and park your router there.