If you haven’t already, reserve IP addresses for all regular network clients. I recommend Factory resetting BOOST before your next attempt. Don’t Factory Reset any other SONOS units without further consult.

BOOST and other older units can build SonosNet, a private mesh network that will ignore WiFi and WiFi ignores SonosNet. If you can wire at least one other appropriate SONOS unit, BOOST is often extraneous. The very newest units, MOVE, ROAM, and the ERA’s do not participate in SonosNet. If you are using SonosNet and multiple units are wired to UBIQUITI, make sure that the switches are set for STP.

Ubiquiti and Sonos can take a bit to get them working together but it can be done. I have used a Boost, a wired Sonos speaker and WiFi connected Sonos with my Ubiquiti gear.

After you reserve the IP addresses start here:

However this is Amplifi, it requires no configuration, unlike the “pro” gear that Ubiquiti have which requires a Masters degree in networking.

I have two homes with Amplifi gear and two Sonos systems in each, never had to do anything special to get them to work. One has an HD and two Instants, the other has four HDs.

You shouldn’t even need a Boost ( or reserving IP addresses) as Amplifi understands how to pass broadcasts correctly and has a much stronger wifi chipset than older Sonos gear.

Something fundamental seems broken with your configuration, this is the first time ever on this forum an Amplifi user has reported a problem (to my knowledge).

Thanks for all the advice.  I’ve read several places that Sonos systems like to have a device plugged directly into the router or Amplifi.  My app actually suggested this which is one reason I bought the Boost to begin with.  Do you think a Sonos Connect device plugged into the Amplfi would help satisfy this need?  My router is in a closet so I don’t want to plug in a speaker.  

I doubt it as the WiFi chipset in the Connect is a poor substitute for that in the Amplifi but if it’s easy to try then why not?

UPDATE - I finally broke down and called in a networking professional.   As it turns out I had a wire from my router to the amplifi unit and then had another wire from the amplifi back to the router creating a loop.  I’m surprised the wifi was working at all.  Once that got corrected all the problems went away, the amplifi mesh points started working, so we ended up not needing the sonos boost at all.  I greatly appreciate the feedback and hopefully this thread will help someone else having issues.  Cheers!