In my opinion having ethernet cables connecting WiFi access points is the gold standard. The exact same data stream that your modem feeds your main router will be the exact same quality, speed that the router feeds your other bridged WiFi transmitters when tethered together via cat 5e or cat 6 ethernet cabling. If your router is getting 900 mbps, so will the next device in the ethernet chain. If your AppleTV is hooked via ethernet to that remote access point, it will be getting 900 mbps. No degradation or slowing of data rates found in typical Wifi "boosters" or Wifi repeaters people place in different areas of their home. That being said it may be near impossible in many cases to string that much cat 6 ethernet cabling unless you're willing to pay hefty amounts for someone to run it thru walls, attics, basements, etc. Often needing drywall repair etc. Thankfully mesh wifi systems offer a good compromise in all but the most demanding situations. WiFi 6 (and later 7 and 8) will continually improve signal transfer quality and reliability.
Mesh network versus a simple Wi-Fi extender
In anyone’s experience, does implementing a pricier Mesh network yield any sonic advantages to just using a good Wi-Fi extender and running a good Ethernet cable from that? From people who have very good streamer setups it seems like using a simple but good Wi-Fi extender from TP-Link etc. is more than fine. Thoughts?