Best answer by Ken_Griffiths
Warnings about using Access Points, Extenders and Power-line Adapters
"Networks using wireless range extenders are known to cause issues with Sonos systems that are configured in a wireless setup."
"Ethernet over Power devices (also known as HomePlugs or Powerline adaptors) as well as WiFi Hotspots are not supported by Sonos."
"If you are using multiple access points, make sure they are all set to the same 2.4GHz wireless channel."
Also, a warning message sometimes appears on the controller when attempting to group players hung off an extender. This can also be triggered by meshed WiFis. Grouping may still work, but potentially suboptimally.