How do I switch from Wi-Fi to Ethernet cables?

Your best bet is to pull your modem out of the basement.  Have your ISP  company move it , thats a horrible spot for Access Point.     If you cannot  do that have someone run Cat6 in the walls to a spot where you can put the Router within the main living area.    The Wifi should be good enough if you pull it from the basement.  You can then also get a switch or use the RJ45 connections on the router to run the cable to the Blue Sound once you move it.

Do not use repeaters they are garbage and never work.  Repeaters half the bandwidth and you will have drop outs.  Even many of the consumer Mesh systems are just fancy repeaters unless they have three radios in the devices to connect. None of that will solve your issue and you might as well just stick with Wifi.  

What router are you using?  is it your providers?  Make sure its the latest as most ISPs provide WiFi6 routers these days.  if not get a Wifi6 router.

@12many Exactly.

@mahler123 

Banking does absolutely require reliable data transmission. As an example, do a search on 'swift financial messaging services'. You'll see just how much reliable data transmission factors into banking.

Even visiting your own bank's website requires reliable networking. Otherwise, you wouldn't see a little locked padlock next to the URL in your browser window. Cryptography would be useless if bits were being changed. Nothing would ever be validated.

You can test this out yourself on Windows using the 'certutil' program on the command line to generate hashes of your audio files. Make a copy of an audio file. Use certutil to generate a SHA256 hash on the original (e.g. 'certutil -hashfile <your_file> sha256'). Then right click on the copy and select Properties. Modify one character of the metadata, e.g. increment the year - if it says 2008 change it to 2009. Apply your changes and run certutil on the copy. The hashes won't match. Another scenario would be to upload a file to Google Drive and download the copy. The hashes wouldn't match if bits were being changed in the process.

Timing issues are minimized because there are multiple buffers for data - from the physical network interface card, to the operating system, and finally at the application level (i.e. the music player software). For example, I use moOde and the playback buffer is 4 MB. For 192 kHz / 24 bit PCM audio, that's almost 4 seconds worth of music.

Besides, I think many audiophiles would be surprised at what jitter actually sounds like. Here's a link to a website that gives you several examples with a pure 1 kHz tone and then with music - http://www.sereneaudio.com/blog/what-does-jitter-sound-like. There's also this - http://archimago.blogspot.com/2018/08/demo-musings-lets-listen-to-some-jitter.html.

I use power line adapter. Google it.

 https://www.howtogeek.com/210895/how-to-easily-extend-your-home-network-with-powerline-networking/

Plus 1 for the Powerline adapter.

Had mine a couple years now and it’s solid as a rock.

NETGEAR Powerline adapter Kit, 2000 Mbps Wall-plug, 2 Gigabit Ethernet Ports with Passthrough + Extra Outlet (PLP2000-100PAS) https://www.amazon.com/dp/B0778Y6K6N?ref_=cm_sw_r_apin_dp_3PP9TGBV3EGDQQ9STFCK