Thank you for taking the time to post and welcome to the Bose Community.
I apologize for any trouble you've had hooking up your Solo 5 with your Epson 2150 projector.
You state not getting audio through AUX on the projector, but you mention "Bluetooth does work" - is that for audio output? Have you tried using the Solo 5 with AUX with something else, such as a TV/mobile device? It might be the case that the projector does not prioritize AUX for audio output.