Tidal suggests 10Mb/s for 3 or more FLAC streams, and no less than 5Mb/s for a single stream. What is the data rate for your modem?
I have a >4000sq ft house and I use an extender.
The house is long and the cable modem and the AC1750 WIFi router is in the basement at one end and an AC1750 extender was added in the middle to get acceptable use of the internet throughout.
My Spectrum connection is 120Mb/s on a good day, so the fact that it is split equally between the two routers is generally of no consequence as far as Tidal is concerned. However, there are times when Tidal is stalling and buffering and that has nothing to do with the internal wifi set up but everything to do with Spectrum (and /or Tidal). I've run internet speed tests when these events occur and sometimes it's Spectrum- it can drop down to less than 20Mb/s- or Tidal that's at fault.
The speed of the main router is 650Mbps for the 5GHz connection and for the extender 350Mb/s so neither is the bottleneck. The 5GHz connection largely immunizes the system from interference from microwaves, cell phones etc. Running ethernet would not, alas, improve the situation in this case.