Projector 3.5 aux jack to Sonos Beam

Not well, a 3.5 inch audio jack will be stereo, not the full 5.1. You’d be better off getting an HDMI switch that has an optical output, which can carry a 5.1 signal, and connect that to a Sonos adapter that plugs in to your Soundbar.

Which Sonos soundbar do you have, there are several?

edit: for that matter, which projector do you have? The more information shared, the better the suggestions will be. 

Sonos Beam soundbar. Optoma projector (used for golf simulator and using other HDMI with a fire stick for tv, movies. 

Yep, I’d stick with my suggestion. Pull off the audio via optical with the switch (look at Amazon for examples) before it enters the projector. It’s covered over and over in this forum.
 

You can then run optical from the switch to the adapter I linked, which then plugs into the Beam. 

Appreciate the attempt, Bruce. I’ve bought about 10 products on Amazon and BestBuy and no luck.  Sonos tech support says it’s not possible and was hoping to avoid buying a new projector. 

Odd. Out of the hundreds of people who have posted in this forum, you’re the first to come back and say it isn’t possible. 

I just don’t know, I’ve never needed to try it, but it sure seemed to be feasible.