I would feed the ethernet cable through the walls and put a jack on the wall. Makes life so much easier.
Seems your modem is part router, otherwise not sure you’d have Wi-Fi.
Once you have an ethernet Jack on the wall, you’ll have a better connection to feed a network switch that can provide digital Signal more conveniently to a lot of different destinations
Don't complicate your life with all this extender stuff. It's not rocket science.